Another vote for Dr Stott! (Arundel Equine clinic). He is GREAT and services all of calvert, and he will make barn calls (with the most reasonable farm call fees I've found)
I used Tidewater all the time Dr. Lisas is awesome, but this past spring used Dr. Stott and loved him. And yes he is the cheapest around I found on farm calls. Good luck with your mare and hope she is alright.
Dr. Mende or Dr. Stott are the closest and I love/have used them both. Tidewater is also great but can be kind of far away. Dr. Molesworth... I have used her once and that's all it will ever be.