My period ended last friday july 4, then started again yesterday july 10. should i worry?

Hopefully not: Irregular periods are extremely common and can have many many differing reasons including stress, excercise, thyroid dysfunction and the list goes on. Also of you are on an oral contraceptive and you missed a pill or two- breakthrough bleeding can occur. I would monitor the trend and see a doctor if you continue to have irregularities .

Depends on Many things: This depends on whether this is the first time something like this has happened, or if this continuously happens and your OB/GYN doctor needs to be aware of it? This also depends if you're on or off birth control pills, and also other medical conditions and other factors that we don't have your full history to provide more help. So please discuss this with your PC P/OB/GYN first.

Irregular periods: It sounds like you are having hormonal issues. Having frequent periods like that can cause anemia pretty quickly. It could be a one time thing, which would be fine. If this happens again, I recommend you see a doctor who may check your hormones and rebalance this as indicated. I wish you the very best!