Tex, I sympathize. I also have clots for no apparent reason, and I do not use gear. My dopplers showed nothing, until the day I had multiple DVT's and a major clot in my inferior vena cava!
Has your doctor suggested maintaining you on Coumadin (warfarin), the blood thinner? It's very inexpensive in the generic form, and very effective at preventing clots.
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Yes, I DO have Male Answer Syndrome.