Please help terrible pain weeks after deep filling

[Curl78]

Hi,please if someone can give me any advice or have had similar I'm going back tomorrow but I'm nervous as a good 4 weeks ago I had a filling done that wasn't even sore to start with she said it was deep well I've had plenty and 2 root canal and no problems or pain after at all so all fine done but straight away I had strange pain all around jaw and mouth could barely open my mouth and my gum etc awful but the tooth was ok well a few days later that settled but the tooth pain yikes!really severe it doesn't stay it comes and goes and lasts a few minutes but it's really bad so I went back after 2 weeks thinking it's not settling getting worse saw a different dentist who said it was really deep and she had to pull the gum back and pack it?? Or something so leave another 2 weeks to settle tried telling him was tooth too not just gum anyway so even tho the pains so bad thankfully it comes and goes so I've put up with it but I can't anymore so am going tomorrow but what could be wrong?i know fillings sometimes go wrong but not this quick?its like she's missed something or I don't know so I don't know what she'll do I can't afford a root canal at the moment and if it was that bad why bother filling it to start with thanks for any advice