Just to add - there are other things that are not pregnancy-related that could explain your symptoms. For example, you might have a UTI or kidney infection. Keep a close eye on things and be sure to see your doctor if you have any concerns.
It depends on when (if) you got pregnant. Pregnancy symptoms can start ~10 days after conception and a HPT test can detect HCG this early too under the right conditions (FMU, sensitive test) - most tests are reasonably accurate about 14 days after conception.
If you ovulated shortly after your period ended (which can and does happen) then you could have enough HCG in your system to experience symptoms and a HPT should give a positive result at this point. Another option is you got pregnant last cycle and had bleeding that you thought was your period.
I would recommend you take a test and if negative, retest again in a week. Also, really watch the one-sided pain - if you are pregnant that could be a sign of an ectopic pregnancy.