are your dragons male and female? male and male? or female and female? these combos have an effect on how they interact.
make sure your providing them with the correct temps. give him a warm bath every week for about 15 - 20 mins so he can gain moisture and hydrate himself then pat him off dry
apart from that i would take the dragon to get a check up and maybe an x ray to make sure he is not impacted. Try and get his poop analysed for parasites. If all that is done and there is no problems then don't worry he is just in brumation. He will eat when he likes.