"I know I'm infected with flukes and roundworms coz I saw them, and probably Tapeworms"
-- you *really* need to get that tested, and if true, dealt with as soon as you can.
If you do have internal parasites still then your body can't absorb nutrients - they steal them from you. Not only do you have little chance of recovering if this is true, but that may the root cause of your issues including lack of ability to add on weight.