Help! He use to sleep!

My son is 10 weeks old. He use to sleep in his in cosleeping bassinet just fine for 4 plus hours at a time. I would nurse him to sleep and place him in bed and he would stay asleep. At his 2 month appointment i got the go ahead to stop waking him for feeds after 4 hours. I was thrilled thinking he would for sure sleep atleast 5 hour stretches since i would have to wake up a passed out baby to feed him at 4 hours. Boy was i wrong. Im not sure if this has anything to do with it but he was vaccinated at his appointment and the next night he was so uncomfortable with gas that he would just scream unless he was nursing. Everytime i would think he nursed to sleep i would put him down and he would be crying within 10 minite and we would start the process all over again. I am now on night 6 of only getting a little bit of sleep because i have now just started holding him all night. Even with me holding him he wakes every two hours uncomfortable and wanting to nurse. I am exhausted, sick with a head cold and just want my little sleeper back!