Welcome! I am Dr. Altman, a licensed veterinarian and happy to answer your questions today.
I am so sorry to hear Charlie is not feeling well today. I suspect the leg lameness
is likely related to her discomfort versus coming into heat
Ideal is to have your veterinarian evaluate your dog to definitively diagnose the problem and start on appropriate medication to control the discomfort. Until you are able to do this please restrict activity (which often they are already doing themselves but that means no steps/ stairs and only carrying to go potty) and rotating warm and cool compresses on the leg in ten minute intervals to reduce pain and increase blood flow.
You can also do light circular massage up and down the leg to stimulate blood flow if this is not too painful and will allow it.
When going out to go potty please leash her and use a towel in the groin to assist her in moving and minimize possible further injury to the leg. If she is having difficulty settling you can try some benadryl 1 mg/ pound to help sedate her a little and allow her to rest. I would avoid over the counter pain medications as it will interfere with what the veterinarian will dispense tomorrow when they open. But if she is going several hours without resolve and she cannot get comfortable or lay down even with the benadryl I would consider a veterinary er today to give her relief.
Please let me know if you have any additional questions I can assist with. I hope you are able to get Charlie comfortable soon, truly.
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