Same thing is happening to me bro.. But someone told me to excersice and drink protein and if you want to get fat and puffy fast drink creatine. Creatine will just add water to your muscle to make it buff faster and easier but you got to keep drinking it. I got the same problem. Im 17 height 5"9 i think or 5"10 and weight 115lb. Is embarrasing but im going to work to buy my protein and work out. Hope this Quote helped you.

I'm not really sure drinking creatine is a healthy way to go about it. I think its under study especially for teens (I'm assuming you are a teen).

Try increasing your calorie intake. Eat healthy, but eat more nutritional foods. Up mostly your grains and proteins. You may need to substitute some thing you like for other things. Like say you substitute a bowl of surgary cereal for a bowl of oatmeal.

How old are you?