The problem I am sure you will appreciate with birds to that they do a very good job of covering up when they are sick. This is because as a prey species, attention to your illness will make you a target for predation. This means we are often the last to know when our birds are sick. Therefore, this may be the only hints we get that something is brewing until the issue is too advanced for Winston to hide. If your wee one has been puffed up and floor-sitting, it does suggest that he is not feeling quite himself and this tells us that something is brewing and challenging his immune system. These signs are very characteristic signs that this we see in a generally poorly bird (just as we suffer from lethargy, decreased activity when we are ill). The fact we are seeing it now, suggests that his ability to compensate with this ailment is starting to wane. With this in mind, we do need to closely monitor him at this point. Eye discharge in itself can be an indication of bacterial infection of the eye, as well as traumatic injury. We can also see eye discharges as part of respiratory disease, as well as more sinister diseases like asperigillus, and psittacosis. So, if we are seeing discharge at the eye then we do need to address them, as well as monitor for other signs of this potential disease process (ie. runny/changes to his stools, sneezes, nasal discharges, a change in appetite).
Also, consider making sure his diet is meeting his dietary requirements, since deficiencies can occur if birds are on all seed or imbalanced diets (ie. low Vitamin A), and these can make them more prone to illness. This deficiency can cause runny eyes as well. Overall, I would advise that it would be prudent to consider having a check up with an avian vet. Eyes are delicate organs, and leaving this to fester could lead to long term issues for him. As well the vet will be able to examine him, listen to his lungs, and analyze his feces (to rule out gut illness or parasites). Depending on the vet’s findings, they will be able to advise you on what might be the causative agent and whether anything needs to be done treatment wise. At this point, we are limited to what we can do at home. I wouldn't advise blindly trying to treat his with anything at from the pet store, since pet store medications are usually unhelpful (wasting time and money and not helping our birds) and you cannot be sure what is actually causing his to show these 'under the weather' signs. Therefore, you would be treating in the dark and guessing what might help.
Hopefully, with some monitoring on your part and a check up with his vet, you will be able to focus on what the trigger for these signs are, and thus treat his effectively and nip this in the bud, before it becomes something that is too advanced to treat effectively. In regards XXXXX XXXXX you can do at home, supportive care is always an important part of helping our birds. First off, consider moving his to a cage that is all one level (no perches), where he can be in easy reach of his food and water. You can cover the floor with something soft like a washcloth or towel. You can place a heating pad under half the cage (so he can choose how warm he wants to be). Alternatively, you can use a ‘rice sock’ to give his cage a bit of warmth. To make one, you can use a clean sock, and fill it 2/3 with uncooked white rice. Tie it closed and microwave (approx 1-1.5 min). Make sure to shake it before adding it to the cage, to allow the heat to distribute. Make sure its not too hot (as we don’t want to burn the wee one. If it cools, you can re-warm as required).
If starts to show a decrease in his eating and drinking, then tempt him with his favorite foods, hand feeding if necessary. And you can also supplement his diet with high nutrition foods with high water content like cucumbers, Romaine, grapes, melon, etc. You can even give his a bit of hard boiled eggs mashed for some extra protein. Cooked brown rice, cous cous are good for them too. You can also give his a bit of pedialyte to drink, if will take it, as it will give his both hydration but also some electrolyte support.
Overall, I would advise monitoring his for more specific clinical signs and considering having his checked over by his vet to make sure this is just an ocular bacterial conjunctivitis rather then the start of something more sinister and systemic. The sooner we know what is causing him to feel so under the weather, the sooner we can effectively treat him and get him back to himself.
If you don't have a specialist avian vet, you can check where you can find one at near you at http://www.aav.org/search/, Avian web (LINK) or Birdsnway (LINK).
I hope this information is helpful. Please let me know if you have any further questions. If you have no further questions, I would be grateful if you would press the wee green accept.