I believe I may be pregnant; no more than 1.5 weeks if so, as that is when I had my IUD removed. (for the past roughly 5 days I've been dizzy, had constant low-grade nausea, huge mood swings, etc. My period was due to start today, I've not taken a test yet.) Today I felt a small pain in my lower abdomen and upon inspection found a hardish lump that hurts when pressed on. It is approximately 3 finger-widths up from my vaginal area and 4 to the right of my left thigh. Is this some symptom of pregnancy I've never heard of, or something else I may need to be worried about?

It isn't a symptom of pregnancy.

I wouldn't take a pregnancy test until you're at least 2 weeks late for your period. When you do, use first morning urine. If it's negative than wait until your next period is due and test again if you miss it, or go for a blood test.

Good luck.