Salamu Alaykum, Sister. I wanted to respond because I hate to see a question go without comment. I and my DH have not been to counseling, and in fact he claims he would never even consider it--especially from a non-Muslim professional. He takes the idea of our being garments for one another very seriously, and would invite no third party into any discussion about our relationship. He also sees a lot of dysfunction in colleagues' marriages and chalks it up to value differences...I could go on but it's not really relevant.
I can relate to your description of dh's behaviors when he is not feeling good and how it affects you, though. My own dh and I went through truly terrible times for several years. He is easily depressed, depends a lot on hard physical work to stay of sound mind, suffers with SAD and we live in the north, and he's far from all of his family.
He does still relapse from time to time. Of course he wouldn't think of taking medication--I wouldn't push it on him, but the SAD household is difficult come winter--but finally after 12 years married he has come to recognize stuff.
For my part, I have done a lot of work separating myself from his illness (I don't cause it and can't cure it). I encourage good health in every way I can. I encourage and support trips to see his family as often as possible. It's not perfect, but we've done a lot to make it better. Getting as close as possible to eliminating TV is huge for us, as is eating a clean diet and having a relationship with nature. Finding just a few families to have close friendships with also has helped. We are not closely entwined with the larger social group; we know everyone but don't feel sucked into it too deeply.
Also, what I've found too much is that the imams we have are very young and inexperienced in life. They can offer suggestions from Quran and Sunnah, but no life experience to back anything up, as they are 5 years younger than we are, two years in the US and one year married, kwim?
and support to you. Can you at least see if dh will explore with you what triggers his negative feelings?