Desperate

Someone please help. My son has barely slept at night for the past 3 nights. And when he starts to go to sleep he moves so much just to wake himself up he used to be a really heavy sleeper but if I move ANY. He wakes up. I’m going nuts. He won’t finish his bottles. He usually eats 5oz now he’s eating 3. Had really bad diarrhea. When I put him down he sleeps until at least midnight then wants in bed with us. After midnight he refuses to stay asleep. Wakes up at least every hour. Is he teething? What can I do? I’m so tired and just want a couple of hours :( I forgot to add he will be 3 months on the 20th.