I have been taking Doxycycline 100mg twice a day for about 10 day...

I have been taking Doxycycline 100mg twice a day for about 10 days now. It has for some reason effected my joints. It started in my knees and seems to be moving to other joints like my wrist. I did see other posting with the same problems, but not a lot. I also had one day of being a little light headed early on but it didn't last more that a few hours. I do a lot of sports, so having knees that hurt and I have trouble using sucks! I am done taking the drug and hope to see improvement shortly, but really have no idea how long before my knees may feel normal.