i would like to say that this is normal, and you are doing the right thing by holding him and doing whatever it takes to keep him calm and happy, even if it doesnt seem to work, you are there. crying in mamas arms is MUCH better than crying alone! :D
i think it is probably teething. has he just learned to turn over or anything? cuz that could interrupt sleep too. i would assume that at some point the night sleeping part will change too many many times over the next year. sleep is not ever a constant.
just keep responding to your kid. try a little teething gel, hot or cold rags for him to chew, or tylenol, whatever your preferred teething methods are. i HIGHLY recommend hylands teething gel. its natural, unlike oragel.
but just keep responding to him and stuff. you could get a sling which might help. i LOVED the moby wrap and i can even still use it with my 21 month old son, although he would MUCH rather just walk than be carried LOL. it is comfortable for all different types of weight. thats the best part. i highly recommend that.
listen to your instincts they will never steer you wrogn!