A new desk chair would probably help--but the nearest place to try them out (Staples) is almost an hour and a half away, too far for me right now.

Most days, almost anything touching my hamstrings makes the muscles tighten and/or spasm. It's kind of hard to sit in a chair without your hamstrings touching anything.

I'll have to read through the responses again tomorrow--my brain isn't processing well tonight. More like a shredder than a processor.