It sure sounds like a Gout Flare. With a Uric Acid at 8 mgs, even on Allopurinol, you are susceptible to Gout Flares. Gout can start in your Big Toe, or several toes, then spread to your ankles and progress higher if left untreated.
Questions…How old are you, how long have you been on Allopurinol, and how many mgs are you taking? If you have just started on Allopurinol, this is a somewhat normal occurence. If you’ve been on Allopurinol for a while (over 3 months) and your Uric Acid is still at or above 8 mgs., you may need to up the dose of your medication. Of course, this will have to be done in conjunction with blood work and under the watchful eye of your doctor. Any doctor worth his/her salt would not up the mgs of Allopurinol without a full blood screening to make sure your kidneys and liver would be able to handle it. That’s why I ask how old you are.
Anyway, your signs and symptoms sound like classic Gout. Use the Google custom search in the upper right corner to help you with Gout pain management. There are many helpful people on this site, and it’s without a doubt the best site on the Web in regards to Gout, Gout information, and Gout management.