That sounds exactly how my sciatic pain started out. Mine didn't really hurt at first. It was sort of like a buzzing or electric sensation that would come and go with a similar frequency which you describe. I have L4-L5 and L5-S1 bulges, one of which is believed to be causing the sciatic pain. Haven't really done anything about it. Now my entire right leg feels like it needs a root canal and I may need surgery. Don't wait long, actively investigate this! I think linder is right that you will likely need an MRI if it bothers you for very long, and then start trying things to head off worse problems.
The shooting pain sounds as though you have a herniated or ruptured disc in the L-4/L-5 area that is pressing on the nerve which sends a shooting pain down the leg to the ankle. I would go to an orthopedic doc if it doesn't improve in a week and they will take an xray and then if needed they will order an MRI of your spine.
good luck