Thanks for using Petco Pet Education Center, formerly Petcoach. It is a little difficult to give specific advice without knowing what type of animal Gracie is; if she is a dog or cat, limping is not typically associated with a heat cycle or something that we would normally see in such a circumstance. If she is limping on one leg in particular, or seems uncomfortable, it could be due to a variety of reasons, including a muscle strain/sprain, an orthopedic issue, or another underlying problem. If it doesn't improve with strict rest for 24-48 hours, or if you are worried, I would recommend having her evaluated by her regular veterinarian to determine what may be going on, and if any treatment is needed. Good luck!