i haven't had the pain post flushing but i do get excruciating attacks pretty regularly.
what i have found is drinking apple cider vinegar in the past. it doesn't work anymore though.
if not too severe a cup of chamomile tea with honey and lemon juice.
i discovered during a particularly severe attack that i do not digest anything while my gallbladder is freaking out/having spasms or whatever is going on. that time i took some prescriiption painkillers and they had no effect on me until about 8 hours later i suddenly felt doped up and painless. the pain meanwhile had subsided some hours earlier. so since then i make myself vomit and have instant pain relief. the body clearly does not want to digest the stomach contents during an attack.
the most constant relief i have found is mintec capsules. not sure if this brand exists outside of australia. it is only capsules filled with peppermint oil. they're also great for the nausea that occurs during the flushes from the ghastly olive oil. i experience pain every time i eat now so i've gotten into the habit of taking one with meals.
good luck with the pain. would be interested to hear if any of these solutions work for you.