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If you have mold in your house, then the joint
pain and allergy could be due to mold. This has to be ruled out by an allergy test. Please consult an allergy specialist. Well, joint pains with rash can also be seen in SLE, psoriatic arthritis, fibromyalgia, polymayalgia rheumatica and chronic fatigue syndrome. Gout, though typically affects the great toe, can cause thumb pain and swelling along with a rash. Hashimotos Thyroiditis is another possibility.