Hi there ~
It is highly unlikely that you are pregnant after you have gotten your tubes tied. The dizzy spells and lower pack pain remains right after you have had your surgery for getting your tubes tied but not after 5 years. You should consult a doctor for the back pain
and also the dizzy spells, get some blood work done and imaging studies like x-rays and CT scans. I suggest that you also visit with a gynecologist since you are having problems with having sex with your boyfriend.
I hope this helps. Take care and have a lovely day !