Stress can make you tense and can therefore make it painful or make you worry about it more. Stress also does affect your hormone levels.
Have a look here under the section "what influences menstruation"
http://www.netdoctor....enstruation_cycle.htm
If you're having heavy periods (which may be what I read into your question) then you are quite young for that, it is always worth speaking to your GP or practice nurse, they are used to questions like that and can usually put your mind at rest, or suggest ways to help.