I was prescribed cephalexin 500 mg 4x a day for a sudden rash on one of my breasts. Then I woke with a new rash all over my abdomen. I’m having severe back pains and spasms, knee and elbow pain, stiff neck, bloodshot eyes, and inability to take a comfortable full breath, and a lot of tiredness. Do I need to be seen again or is this a normal reaction of the Cephalexin?