Need a little help

Advice, support, ideas... Anything

My 3 and a half month seems to be very clingy at the moment. Not sure if he has an upset tummy or what's going on.
He constantly wants to be held and or nursed. Thinking that he may be hungry I start feeding him. He'll nurse for maybe 5-10mins then he'll fall asleep. I've tried putting him down to sleep... Doesn't work. I've tried holding him a little longer so he can get a nap then be happy and alert... Doesn't work. I'm not getting a chance to eat and barely having time to use the bathroom before he starts crying.
I am exclusively bf and my breast don't feel as full as they normally do, not sure if it's due to him feeding more or my supply is dropping.
TIA

Growth spurt, teething, just wants mommy.

sounds like a growth spurt. And some babies just want to be held 24/7.
get a wrap or a sling.