Tommetta the terrapin! help!

[amony]

Hi there, amon here ! I am making a post for my gf, who's 15 year old terrapin isn't too well, here are some of the details:
*Tommetta is 15 years old, she has been pretty healthy for most of her 15 years, she had small problems with her shell due to lack of a light and calcium but that cleared up pretty fast with help from the vet.

She has had some swollen legs recently and lack of appetite. This lack of appetite is nothing new however as every winter she eats less, there were however up until now, no signs of her swollen legs and after winter passed she would regain her appetite, vets would tell us it was just the weather and it seemed like that,until this winter when she appeared to have pink swollen legs that when she was walkin about and drying off, didnt seem so pink anymore but still pretty bloated. My gf noticed this and ofc took her to the vet, the vet said she had swollen liver/inflamed liver, gave her an injection and antibiotic to take home, she is still due another visit to see any progress, her appetite has not returned however and she has had this medacine for under or only just a week. She is difficult to give medacine to however my gf manages to give her it by making her open her mouth by taping her face with the seringe( plastic medacine seringe, dont panic) so she receives medacine and eats very little, she does eat tiny bits of fresh prawns but does not eat her dry food or anything else..
My gf feels like she isnt handling this as well as she could be, is there any tips that could help her to nurse her tommetta back to health inbetween visits to the vets? Here are some extra info. I will post a picture soon. of Tommetta healthy, and tommetta right now.

*She usually eats a varied diet of meal worms, dried terrapin food, fresh prawns, crab sticks and mussels occasionaly and sometimes she even eats lettuce, cucumber and spinach!

For years tommetta didn't have a light or filter as my gf was unaware that terrapins needed this, do not think bad of her please as she loves her tommetta very dearly, she has had her since she has been 5 years old, she is now 20. She now has a uvb light for terrapins above her basking rock, she loves to use this rock to sit apon and bask, even before she had her light, she loved this rock. My gf was also scared of when tommetta slashing water into the light as when its egg season tommetta has had problems with laying eggs , this is a seperate problem that is being solved atm however. My gf was frightened that tommetta would slash water into the lightbulbs and make them explode..harming her terrapin... but she has a light now and my gf will be getting her a filter and a underwater heater as she thinks the waters too cold.
any advice i can give please? please be nice.