Could you get to an osteopath? I saw one and he did great things for my lower back and SI pain.
Diclofenac might be stronger over the counter than ibuprofen though think you can only get it in small amounts. Voltarol do tablets with it in from behind the counter. Pricy but I've found them great in the past.
Maybe paracetamol and codeine?
With the heat patches, add a hot water bottle and maybe a nice relaxing bath with radox (the salts are good too) and dead sea salts and such.
Maybe some pain relieving gel? You can also get the gel with diclofenac in like Voltarol.
Did you have it checked out when you had it before? If you can get to a GP or walk in centre then they could prescribe some more effective pain relief if over the counter isn't cutting it.
Watch your tummy if you are taking lots of anti-inflammatories if it's delicate.
Hope you feel better soon!