I sleep on my side, I have joint pain, especially in my shoulders

Hi.
I've been suffering from some joint pain, especially in the shoulders and elbows. Having spent some time traveling we've tended to sleep best on a deep, soft (or soft feeling at least) mattress, however finding a mattress like this seems to be quite tricky. I also find getting the right pillows a nightmare and this also causes some discomfort (having a different mattress to previously has also seemed to change my neck/head position on the pillow)
We recently (start of November) purchased a casper mattress, however I find this too firm and also a bit sweaty and so we're going to return this. To elaborate, when lying on my side I find the pressure on my shoulder when trying to sleep is uncomfortable, I can get pins and needles/soreness when trying to sleep like this or wake up with this in the night.
I'm 6ft 2, 11 stone, and tend to sleep on my side (or less often on my back). We've a standard double bed.
So, would love to hear what you would recommend as the right mattress!
Thanks
Dan