Far as I remember TigerBalm contains no methyl salicylate, only clove oil, menthol, camphor and a few other oils of that sort.
I can't for the life of me think of any risk to the sperm-count, but then again I'm not a doc.
The biggest risk is from burning or over-irritation of the membranes as Nwah pointed out.
So the best advice I can offer is to check the list of ingredients on the tube, and give the body time to heal between sessions.
In short, don't do anything stupid.
CheerfullyInsane
"Anyone who thinks protocol is unimportant has never dealt with a cat"
- H. L. Mencken