I'm already taking doxycycline for a skin rash. i have a sore throat and fever and was wondering if it will help?

Only if the throat..: If the throat has an infection caused by germs that can be killed by doxycycline, then the medication can help. That's a big "if", because many sore throats are caused by viruses (and thus are not affected by doxycycline). Also, the doxycycline for some rashes may be at a dose that is not right for treating bacterial throat infections.