and sleep vibes to you and your little man.

At 5mths I would consider starting solids. I have only just got DD onto them (she is BF). We skipped the whole rice cereal as she didn't like it and went straight onto weetibix. I also give her toast to suck and munch on which she is doing well now. See if he will even suck on some steamed carrot sticks or vegetables. Offer morsels of food and see how he goes.
Perhaps also take him to the GP and rule out any ear problems...does he have the sniffles or a cold?
A developmental change could be the cause, it wouldn't hurt to give the solids a go now to see if that helps.
The baby led solids thread is a good one to have a look through if you are considering starting solids.

Hope things improve for you soon...it is exhausting no matter how much we love our little people