Can flomax (tamsulosin) cause feeling needing always pee and sore abdomen? Always feel have to hold back urine or go every 20mins

Possible. I need to ask, why would a 30 yo need flomax (tamsulosin)? It does have side effects. Being dizzy is most common. Check with the doc who prescribed it. .
Here are some... Despite taking Flomax (tamsulosin) intending to improve urine flow, you should be followed with the doc ASAP to assure you can empty bladder & have no UTI. To get things done right, follow instructions in http://www.formefirst.com/eNewsletter06.html; thereby, you gain much insight on how to work with doc closely so to reach right Dx for right Rx, care, & counseling.