HI,Dear, Thanks for the query from you for your -big lump between top of the ribs? but its not clear whether its the top of the lower ribs(hypochondriac regions on both sides of the rib cage) of the abdomen or big bump between top of the top ribs(1st ribs) painful lump in your throat.1-I am happy that you are serious to know why this big lump occurs between the top of your ribs-?2-In my opinion this big fist sized lump between top of your ribs(1 st ribs ) could be a-Thyroid with extentions underneath the sternum or it could be -(as at the central angle of the 7 th /8th rib cartilages) "-epigastric hernia- post-pregnancy" due to the strethed out abdominal muscles.3-Most probably it is -Epi-gastric central hernia due to the stretched out recti-abdominis and herniation out of it centrally below the central rib angle, which gives 6 mth pregnancy appearance -even after delivery, especially when you lean back , with increased intra-abdominal pressures.4-This would explain, what is happening in your stomach-its the post-delivery -Central herniation due to the stretched out- Divarification of the Recti Abdominis.5-I would advise you to see the Gynaec surgeon and ER Surgeon-and I would advise hence to treat it with-a-Exercises-to tone up the Recti-abdominis b-with The Abdominal toning belts for atleast 3-6 mhs to reduce the herniation of the big fist size centrally , when one leans back.c-or if no releif ,then surgical correction of the Diverification of Recti -would resolve the issue.6-Hence I would suggest you to go to ER Surgeon for the evaluation and treatment of such cases.7-Hope this would resolve the causative worry of the patient in question .If treated on this line, the fearing patient , should not worry you much.8-Hope this would solve your worry of the big fist size central abdominal lumps on top of the rib cage margins,when one leans back after the pregnancy.9-So urgtly take -the advise from the ER Surgeon.10-Wellcome to HCM for any more query.