My husband has been taking azothiaprim & allopurinal to treat his active crohn s disease. He has developed painful joints, shortness of breath, fatigue, painful calves, noise in ears, noticable heartbeats/ pulse, and loss of skin color/ pallor from head to toe, some decrease in appetite. He has discontinued the allopurinal, but has not experienced improvement in symptoms yet. What causes the pallor/ pale skin & other symptoms & is this reaction expected to improve with discontinuatiin of the drug?