Hi Megg. You won't smell too good, but a mild white vinegar solution might help. It was one that I found when I was searching for natural remedies to SOH's sore nipples. Often itchiness is caused by the pH balance of the skin being out and reintroducing the acidity can help. (Your skin is acidic). My mum always used vinegar on sunburn when I was a child and it worked a treat. (Though obv these days we don't allow kids to get sunburned!)
The other thing I thought of is bicarbonate of soda. It's my super-duper rememdy for itching with chicken pox. Put a load of it in the bath and wash it over your tummy, or make up a solution and bathe the area.
No idea if they'll definitely work, but both are cheap and worth a shot imo.