Thanks for writing to us,
Are you obese
? do you drink alcohol regularly?
You may be suffering from lumbar muscle sprain
,or spinal disc bulge which can aggravate on lying down.
If you tummy is large increased pressure may lead to pain .
You need muscle relaxant
and neurotropic .
I f you are drinking alcohol then these symptoms can be due abdominal fluid collection . you may need USG abdomen to further confirm.
I hope that I have answered your query. Let me know if I can help you further. Take care