Miscarrying or not? Some symptoms and very confused.?

Last night it felt like my cervix must have been open. I am just under five months along. I am uming I lost my mucous plug, I had a blood tinged snot like discharge/jelly. I checked this morning and it's a little open but not much, and I have some light reddish brown barely discharge. I don't have an OB yet, just moved here a few weeks ago. Is this a miscarriage ready to begin? Been having some light twinges and a bad backache.