I don't think you are too late for the match. It would be best if you had your application in by Nov 1st, but many programs take apps until Nov 15th or Dec 1st, or later.
You are welcome to call IM programs if you wish. Since almost none of your FP training will be transferable, you'll need a PGY-1 spot. PD's are starting to work on filling their PGY-1 spots by interviewing candidates. Hence, I think your best option is to get your ERAS application done and in -- since you are already in training it should be relatively easy. You should have most of what you need already, except for your LOR's. You'll want to ask your current PD for a letter if possible.
Yes, that means that you will probably need to tell your PD that you are thinking of looking at a new field. There are many past threads on this topic, and no easy answer. You can try to do this without telling your PD, but getting the time to interview can be difficult and many PD's will insist on talking to your current PD anyway.
Good luck!