3 month old not eating

My 13 week old is bottle fed and has been since birth. He eats 5 oz every 3-4 hours and sleeps 10 hours at night. Lately he hasn’t wanted to eat. I literally have to force him to or he just won’t do it. He only seems to want his bottle as soon as he wakes up and that’s it. I’m really worried. Should I go to the doctor? Wait it out? Advice please