I've been having sex actively for over a year. Up until about 2 weeks ago, I have had an extremely strong sexual stamina. It usually takes me a really long time to come--which I actually enjoy. However, the last three times I have had sex, I came extremely quickly. It also seems to be related to positions. When I get on top, it feels as though I'm going to come in a matter of seconds. I've never experienced this before, and I can't really figure out why I would have this sudden loss of stamina, so I'm looking for help on here. If you have any ideas, that'd be wonderful.
Thank you.