16 month old fighting sleep

I dont know what is going on with my 16 month old but I'm starting to worry. Hes normally a good sleeper but recently it take anywhere between 30 mins and 2 hours to get him down for bed. During that time he is in full freak out mode screaming crying throwing his body around trying to get away. I used to nurse him to sleep but now he wont nurse unless he's laying next to me and I cant be touching him at all. I'm not sure what to do its really stressful. We were on a pretty good schedule until all of this started now hes only napping for 30 minutes and is waking up so many times at night.

I really just need advice.