Gaining

Because of a new medication my appetite is SO much lower. Does anyone know any appetite enhancers to help with this problem?

I'm very much into cooking. A thing I do when I feel that I'm catching a flu is to cook (if still possible) some chicken soup. So: when I'm completely sick, it's still something I can look forward to.
Let this be a strategy: what are your favourite meals? And (that maybe just me): learn to cook them. From scratch. 1.: you're in full control of what exactly you're eating. 2.: the variety and quality of meals is amazing!
2 examples: pls look for "Tarte Tatin". An apple cake. And I've lately made "Sauce Bolognese".
(Yes: I DID cook it for 6hrs!) Chef John on youtube describes it perfectly: "Foodwishes" and "Bolognese", and you'll find it.

I take cyproheptadine and it works very well. Mine’s prescribed by my doctor since I used to be super underweight, but if your doctor can’t be convinced that you need it, in some places you can legally buy it over the counter either as an appetite stimulant or an allergy medicine. I haven’t experienced any side effects, although, as with any other medicine, some people do.

I was on cyproheptadine for a while but, aside from some temporary drowsiness, I did not notice any change in my appetite.

I've been able to work around this by just drinking heavy whipping cream on top of my regular diet. I'm drinking 1 and 2/3 quart per day, and this has been much easier for me to do than trying to eat a lot of food.