With Budgies/Parakeets, maturation and readiness to breed may cause a swelling and discoloration of the cere, but so might a fungal, viral, bacterial infection or mites.
In some birds, indications that there may be tumor activity would be a change in cere color, weight loss, changes in droppings (often becoming pasty, soiling around the vent) and just subtle, overall changes that owners may sense more than actually see or be able to describe
My thoughts are that this bird is pretty young to be showing symptoms of tumor activity, which is much more common in birds on a seed only diet; however, it's still possible and the other symptoms do not need to be present (you may have just caught this very early).
Since all of these possibilities exist and many will be treatable when caught early, getting your bird seen quickly is always the right choice.
It's also very often the least expensive way to go (early treatment).
When it comes to feeding to avoid this challenge, which nearly all seed-only birds eventually face, along with liver disease, you might want to switch them to a pelleted diet and be sure to include fresh foods every day.
A diet consisting mostly of pelleted food supplemented with fresh fruits, vegetables, grains and a good seed mix that does not include sunflower seeds, is your parrot's best choice.
It's not easy for some birds to make the conversion, but quite often that's because their owner is too easily swayed by their demands and fear that the bird isn't going to eat at all if they don't get their junk food.
When I take in rescues, one of the most common problems is nutrition. The birds are either terribly underweight or obese. Changing their diet is often a matter of life or death and I haven't lost anyone to date.
I'll try every type of pellet out there, whether fruity or plain, spicy or a combination - just be sure to get the size & type appropriate for your individual bird.
Offer a pellet from your fingers as a treat (if your bird is used to taking treats from your fingers that is) and go ahead and try one yourself so the bird can see. I'm serious - try it yourself. Your bird shouldn't be expected to eat anything that you wouldn't eat yourself.
I've mixed pellets in with cereal too, especially a good, healthy, low sugar type. Try crushing them into an all natural yogurt or baby food of mixed vegetables, sweet potatoes, squash or the like. One of our macaws started to love them when she found them in with her blueberries and other cut up fruit.
I've found it's not a good idea to mix the pellets in with the seeds, but be creative otherwise.
One warning is that if you mix the pellets in with anything wet or even make a ‘mush' out of the pellets using plain water, a natural, low sugar fruit juice - you must remove the dish (must!) after an hour or two, tops. There's too much chance for bacterial growth in wet foods and this only makes a problem worse.
While making the conversion you need to monitor your bird very carefully. I strongly suggest getting regular weights.
A gram scale is one of the best investments a bird owner can make since many illnesses are not noticed until pretty far along. With a regular weight monitoring, you'll know when a weight loss (or gain) trend occurs and may be able to stave off serious problems by catching them early.
I weigh everyone every Saturday morning, right after a dropping. They've come to expect it and happily step up on the scale when it's their turn.
For more ideas and options at conversion, take a look at these links. There are as many ‘right ways' as there are individuals.
No matter what, keep up the good job you're doing with this budgie and the rest. Sharp observations are your best defense against major problems.