Q-Switch or nanosecond lasers have a more inherent risk of complication over picosecond lasers. It sounds like you have significant blistering. Blistering is more common on the lower legs and ankles than the upper body because blood flow is less so healing is slower. Laser tattoo removal blisters should generally be treated like those from a sun burn. Do not puncture (pop) them. If you must, use a sterile needle to drain the fluid, but keep the overlying skin otherwise intact and in place to protect the healing area. We also recommend keeping it elevated as much as possible. Avoid heat (hot tub, hard cardio workout, working outside in Texas in July, etc) for 24 hours after laser treatment and as long as you have blisters. There are several ways to tell if it gets infected: fever or high heat on the treated area (although with swelling, you can expect that area to be warmer than non-swollen areas of your body), appearance of pus or drainage of any color other than clear, if the swelling decreases, then seems to increase again, especially if the swelling becomes hard or painful. You will probably know if it becomes infected-the appearance of the wound will change. If you have any questions about it at all, seek medical attention immediately.