Could The Pain In Thighs Be Due To The Side Effect Of Cephalexin?

I have a severe cast of bronchitis accompanied by a sinus infection and headache from the continuous hard coughing. I have been taking 500 mgs of Chephlexin three times a day for 3 days now and don't seem to be getting any better. I also am on an albuterol inhaler every six hours if needed for wheezing. For the last two days I have been experiencing aching in the front of my upper thighs. I notic this especially at night. Could this be a reaction to the cehpalexin????? Thanks!