At 13 weeks he should be gaining weight daily! So if he isn't, you have to figure out how to get more food into him. Would be best for you to figure out a way to get a proper syringe and baby bird food.
-Kathy
Is he young or just very thin? Doesn't matter... I'd try to get 30 ml of fluids into him 4 times a day. Start weigh him daily and you'll know pretty soon if your treatment is working or not. If he's getting enough to drink and eat he will gain weight.
-Kathy
You should be able to feel the tube as it slides down the right side of his throat into his crop. Make sure the edges of the tube are smooth enough... some people hold a lighter to the end and melt it a little. Make sense?
-Kathy