Hip flexor strain

Hi! I had some sharp left hip flexor pain during a 16-mile long run 2 weeks ago, took a few days off, was completely pain-free, and started run/walking to ease back into things. I ran ~6 miles yesterday morning (10 min running/1.5 min walking) and felt great during, but felt my hip completely lock up/strain when standing in my apartment last night. The pain is pretty severe (I’m not able to walk, lay down completely flat, or sit in a chair without a sharp pain or tugging feeling) and I plan to stop running completely for the next few weeks, but wondering if it’s possible (or wise) to attempt the NYC Marathon in 4 weeks? I know it won’t be my best effort and will likely run/walk most of the race, but should I just call it and defer? Don’t want to do any permanent damage but really want to do it this year…Thanks in advance!