PLEASE HELP EMACIATED CAT

So i have a cat that got lost for almost 3 months. Yesterday he showed back up and he is so skinny!! I cried my eyes out because 1st he's my little boy and 2nd to see him go from 25-30 pound cat to 5-10 ounds at the most is horrible! ! N yes i did look for him and never stopped! ! Any ways he eats and drinks but i noticed he throws up after eating..and he dont eat alot every hr he gets up and eats then lays down. He still is his funny self but seems tired. Now how do i get him fat again? Problem i have with him and other cats i have is they will not eat human food or soft cat food never have and will refuse it idc what you offer them so what can i do for him? It breaks my heart an all i want for him is to be healthy and fat n happy again...PLEASE HELP

First thing is to get him to the vet first thing tomorrow for a check up  and for the vet to assess his health situation.  Be sure to feed him very small servings of canned food every couple of hours, not too much all at one time as his tummy won't be able to handle it, which you're seeing by him throwing up.  Also, don't allow him to drink too much water at once for the same reason.  You can start off by giving him some kitten food and/or some plain meat baby food (no onions or garlic).  Chances are he's got parasites, so he'll need to be treated for that.  Keep him confined if you can until you can get him to the vet tomorrow.  Keep him warm, too.  You might need to put some warm rice socks with him as he sleeps to help keep him warm.

Problem is that he will not eat anything but dry cat food! I have tried everything. Also is it ok to give him nausea meds?

If dry food is all he will eat then give him that but also provide water. Follow the rest of the advice the above poster wrote regarding the vet on Tuesday, and keeping him warm. The vet needs to evaluate the cats condition.

I agree with the advice above. Also don't give him human nausea meds, they can be dangerous to cats. Ask the vet if they think he needs one, they can prescribe a cat-safe one.