Burning pain in right groin when sitting or lying down. Rest of hip and leg aches some when sitting. Less pain when standing walking. Pregnant. Causes?

Unlikely Hip. Typical hip pain that stems from arthritis is usually not described as "burning". However, nerve pain, (called neuropathy) is commonly described by patients as burning, tingling, electrical. The location of your pain in the groin is similar to where hip joint pain would be felt, but your description of the pain gives me the sense that this is a nerve. Arthritis also has stiffness involved.