Urinary tract infections can and will affect your strength and energy! When you're fighting an infection, your body is going to give more energy to that and that's going to wear you out.
I'm not a doctor and this is anecdotal, but when I've dealt with a UTI (a few times) I'm basically exhausted and my energy is sapped dry.
If you haven't already, get into your doctor - the test is a simple urine test, no big deal. If it turns out that you have one then you'll want to give yourself as much of a break as possible while you heal.