Lower right abdomen spasm/pain instantly?

Hi all, 2 years ago i was boxing 4 times a week and had no pain etc apart from ofcourse muscle fatigue after a hard workout. I had a rough bout and since then have ended up with a shaking feeling constantly in my body along with other random muscle jumps etc. If i try and do anything like a snake bend/lower ab situps etc. I get an instant agonising cramp where it visibly yanks upwards for 20 seconds while i squeal like a child until it passes. I occasionally get a milder version when walking but that''s probably 2-3 times a month i notice it. I gained 2 stone in weight since my boxing issue and wonder if visceral fat could be a reason behind it but it just seems strange its on one side. I get the common muscle fatigue in all other ares of my abdomen but lower right side is viscious. I have went to hundreds of dr appointments and they say its probably muscular but im begging for a neurologist (for the shaking issue) to no avail. I have paid privately for a physio and she told me to do planks and bridges to try and strengthen the area but it doesn't seemed to have helped( i probably haven't give it my all though ). Its rather miserable being me right now and constantly feeling like my body is under stress without a reason why. I just dont see how i can go from doing 4 boxing sessions a week with many many core workouts to not being able to do 10 without insane cramping in that side. I don't know where else to turn so i'm praying someone might have lived a similar situation and got out the other side. I am currently 19 stone 4. I was 20 stone 2 weeks ago and decided enough is enough. When i was fit and able i was 17 stone 10 roughly. Thanks in advance and i greatly would appreciate any advice even if it helps me to have hope.