Hello and welcome to e health forum.
It seems that you have a angiomyolipoma, of your right kidney, which your doctors have advised to get treated with selective embolisation of the tumor.
Usually such tumors do not cause any symptoms unless they are very large and are about to rupture and bleed. The pain in such cases would be continuous, dull or throbbing type initially and worsen progressively until proper medical help is provided.
Pain due to arthritis increases with movement of the affected part and subsides on taking rest. Since your pain is only on waking up, it is more likely to be due to arthritis than due to the lump.
You might consult with your doctor who can help you to deal with the pain and provide proper treatment.
I hope this helps.