Thats ok I completely understand Thank you for the additional information and if you could take a temp when you get home that would be great. Normal temp is 100.5-102.5
Lethargy is a very broad symptom and can be do to far to many things to cover.
With the previous sneezing, watery and gunky eyes that developed only a few days after getting out one concern would be that she has contracted an upper respiratory infection.
You can read more on this here
The Herpes virus is also possible( not contagious to humans). This is the most common cause of sneezing and eye discharge and can flair up at any time.For this we normally treat with L lysine which you can get at most pet stores or health food stores. 500mg per day for 7 days then 250 a day after that. Since this is a virus it simply has to run its course.
Here is detailed information on this
Fever can also cause lethargy so if her temp is over 103 when you get home she should be seen by a vet right away.
The fact that she is still eating and drinking is great as this is a great judge of over all health. Most cats that are very ill or in extreme pain will not eat.
With her not being able to jump this could be weakness due to URI or it is possible she got into a fight or was injured outside. Check her over really well for any lumps that could indicate an abscess.
Since she begin this soon after going out it is impossible to know for sure without an exam if she was injured, exposed to a sick cat etc.
I would take her temp this evening if it is normal I would just keep an eye on her. Try the L Lysine and make sure she continues to eat. If she stops eating even for 1 day , she has a temp or you find any lumps or injuries she should be seen right away.
I hope all goes well, please reply back if you have additional questions or concerns