I have always had a very regular cycle, 29 days apart that lasts for 3 to 4 days. For the last month I have started bleeding every ten days lasting 2 to 3 days. It starts as very dark brown then to bright red. I am away from my husband right now and I wonder if maybe it's because I am not having regular sex. I don't have the normal symptoms at these times, the bloating, breast tenderness, cramps etc. it's just a sudden onset. Any idea what may be going on?

Could be your hormones, and you, are missing your husband !

The older you get the less regular they become.. I would go to obgyn.