I have been taking allopurinol for 1 week. I now have a gout attack. Can I take colchicine as well? I

Wrong order! Taking Allopurinol during an attack will worsen and prolong it. My regimen is this: establish diagnosis. You can start an nsaid, inject the affected joint(s) with steroids, start colchicine, bid is adequate with the other meds. After three days start Allopurinol 100mg x 1wk, 200mg x 1wk, and then the full dose. The cochicine can be cut back to once daily.
Yes. You should never be started on Allopurinol alone as it commonly can precitpitate gout early in the treatment. Always take Colchicine 1 tab daily with it until your serum uric acid level is stable at 6 mg/dl or less. Hold Allopurinol during the acute attack and treat the attack either with Prednisone or nsaids. Colchicine is not my first choice for acute attacks.