I am SO sorry to hear this @cranky_granny - you should NOT be in pain.
If your tummy is churning & you've been taking your max drugs (specially if they include ibuprofen & other pain killers/anti inflams) you may have compromised your stomach (the same happened to me some years ago with a hip problem .... the anti inflams had started aggravating my tummy.). You may need an 'uppie & downie' to assess any possible damage.
Can you talk to your breast care nurse, Onc and/or GP for an urgent pain/treatment assessment (get your BC Nurse to ring the GP/Onc if you are not up to it, for an urgent appointment? GPs always have some spots available every day for unexpected situations just like this) .... your pain needs to be addressed NOW, not next week!
Dare I say it - speak with your GP about the possible use of Medicinal Cannabis Oil - you should be able to access the strongest available - altho sadly, it is still expensive even going thru the GP/Pharmacy access ...... message me if you'd like more info xx
take care - I hope you are seen today or at least tomorrow xxx