Hi Lainee,
Just went through my first bout of canker sores in years. Nasty little buggers. Had one on my tongue that hurt like hell. Now rinsing 2x/day with Listerine (aerobic mouthwash) and taking Lysine daily. Can't remember the dosage of my Lysine tabs--rheumy just told me to take the adult RDA listed on the label. Dentist recommended Oragel (benzocaine) maximum strength. Insert a clean Q-tip into the bottle to get it really wet with the stuff, then lay the Q-tip right on the sore for as long as you can (a few minutes if possible)--the longer, the better, he said. It helped with the soreness in all of mine except that one on my tongue. Nothing helped that!
Rheumy said the sores can accompany auto-immune disease, could occur as response to physical or emotional stress, and are a side effect of many meds used to treat PsA, including MTX.
I do recall years ago, a dermatologist I was seeing for psoriasis at Cleveland Clinic told me about mixing Milk of Magnesia (some people use Maalox) with 3% hydrogen peroxide and rinsing with it. Google proportions to be sure, but I think it's 1/2 and 1/2. The peroxide is aerobic (introduces oxygen) for the mouth. Anaerobic bacteria (the bad guys) can't thrive in the oxygen rich environment. The MOM coats the canker sores and is supposed to be soothing. This is a variant of what docs call "magic mouthwash," a compounded wash that also contains prescription ingredients: http://en.wikipedia.org/wiki/Magic_mouthwash
The eye symptoms you describe sound awful. Sorry you are having such a time of it. I've had a sort of conjunctivitis pretty regularly over the years that they tell me is PsA related. So far, I've been lucky to manage it with steroid drop samples from the optometrist. Itches like heck, causes tearing and reddish eyes. I developed little fluid-filled "inclusion" cysts on the whites of the eyes, also typical with psoriasis. Sometimes they have to be lanced, but mine have always resolved on their own. So far, nothing as extreme as you are experiencing.
I have to say, I might consider trying another rheumatologist. Anyone can have an off day, but when a doc routinely blows me off, then they aren't addressing my needs. I'm not only wasting time and throwing my money away, but also not getting the relief I sought in the first place. I've encountered a few like that over the years and I know how discouraging that is. It certainly doesn't help anything!
It's not always easy to change docs for various reasons, but your health, comfort and peace of mind are important--in fact, they are the only reasons to go see a doc at all. If your doctor isn't filling those needs, then he isn't helping; he's hurting. Maybe your dermo could provide a referral?
I hope you are able to get some relief soon! Keep us posted.