What Causes A Soft Large Lump On The Pubic Mound Area?

This is so embarrassing but trying to decide if I need to go the ER or just chill and wait a few days. Thanks in advance for any advice and no don t worry I won t hold you accountable for anything I choose so please just tell me straight up what you think. I m a straight shooter and appreciate docs who are as well. I m a 49 year old female, non smoker, no alcohol or drugs or prescription meds. I am a lifetime distance runner (about 30-40 miles/week comfortably) and just started taking boot camp type fitness classes which focus on core strength which is very weak for me. I don t strength train on my own. Today I noticed a golf ball type lump on top of my pubic mound area. Got in the shower, it wasn t there and after a few minutes I looked down and was shocked to see something the size of a golf ball. No pain, and it s very soft. When I lie down it disappears. I try to push it back and it recedes a little and then comes back. I took 800mg Motrin and rested and saw no change. I have no fever and no other soft masses like this anywhere else. Do you think it could be a hernia? Or should I be alarmed? I wish I didn;t look up symptoms of all kinds of horrible stuff online. Any advice would be appreciated - thanks