10 days after tick bite. bite healed but around it is a rash and is very red.

Maybe tick rash: The rash from a tick bite is usually annular and resembles a bull's eye. If the tick was attached for longer than 24 hours and is full , I.e. has eaten you are at risk for Lyme disease. The treatment varies from 1 dose of doxycycline to a full 10 day course. The tick that places you at risk is the black legged tick. If there is any doubt see your doctor and take 1 dose of doxycycline.

Lyme Disease: Sounds like it may be Lyme Disease. Does the rash resemble a target (that's practically diagnostic of Lyme)? Treat with Doxicycline 100 mg twice daily for at least one month. Follow up with physician familiar with Lyme.

Bullseye rash?: It is common for the area immediately around the bite to be red, but if there is a clear area around that surrounded by a red ring that is a sure sign of Lyme. A single dose of doxycycline after 10 days would be worthless. ILADS (the association of Lyme specialists) recommends 200 mg of doxycycline 2x/day for 30 days. A tick bite can also cause Babesia, Bartonella, Ehrlichia & other infections.