lupus?

My pug and I need help! At the beginning of this June I noticed a few scaly patchy spots on his skin that got worse after going out in the sun. Took him to the vet and was dx'd with a skin infection and treated with antibiotics with minimal improvement. In July he developed a scelritis to his left eye and we went to ophthalmology. He was treated with predinose drops x 7 weeks with immediate improvement. He also had some inflamed lymph nodes in his neck. The doctor told us he thought it was an autoimmune disease. Shortly after his skin got worse and his mucous membranes around his rectum, penis and lips turned bright red. Back to the vet and more antibiotics with no improvement. In late July he started losing some of the outer toenails. I started researching autoimmune diseases and lymphoma all over the net. Since he was no better back to the vet we went. I told him what I found and he told me he didn't think it could be lupus and thought it was probably lymphoma and wanted to do a lymph node removal to check. On his liver panel he has had a slightly elevated ALT for approx 8 months and has been getting milk thistle for that. No other elevated liver enzymes and his complete blood count was normal including platelets and hemeglobin/hematicrit. I asked that we try prednisone before going through a surgery. He prescribed Prednisone 20mg 1x per day for 5 days. Then 10 mg every other day as needed. Once again after just one dose the lymph nodes decreased in size, his skin got better and his mucous membranes returned to normal. I made an appointment with NC State animal hospital but there is a approx. 3 week wait. We are scheduled to go in this week and hopefully get a diagnosis. Over the weekend he has had acute inflamed nodule under his neck with some slimy drool on the same side. He is acting normally, eating and playing with his toys and brother and other then sneezing, rubbing his eyes with some drainage, and the swelling no signs of illness. Does anyone have any suggestions as to how to pursue and get an accurate diagnosis and treatment to help my buddy? Thank you