I'm sorry to hear about these reactions you are having, that must really suck especially since you do need to take tablets occasionally, hopefully your body just needs time to heal.

One thing I have been told multiple times by multiple doctors though is that endo pain is very rarely able to be controlled by pain relief tablets. I have been prescribed pretty "intense"/strong pain relief tablets (usually given to people after serious injuries such as broken bones ect.) and they done absolutely nothing for me and all my doctors told me this is pretty normal. This could be the reason they are reluctant to give you more/stronger tablets since they very rarely work with endo, I'm not sure why but that's what I'm constantly being told. Also, I'm not sure what the tablets that you are taking are since I'm in Aus but I have also been told by multiple people (specialists and GPs) that ibroprofen actually tends to make endo pain worse and you shouldn't take it to treat endo pain. Again, I'm not sure why this is the case but every single doctor seems to tell me about it when I bring up endo. I'm not a doctor so I would get a professional opinion as well but I'm just passing on the info I am constantly being told.

Honestly, your doctors don't sound to great, if I were you I would try find someone else that is willing to listen to you and help you control your pain better