So you’re in your third week which generally is purée. Can you give us an idea of what you’ve been eating.
Yes, some take longer to heal & therefore need to move through the stages more slowly so move back a stage for a few days. Like the purée you’ve eaten is still too thick for you yet. Try thinning them with water, stock, milk, etc. Some allowed foods can still be too heavy for our tummy yet & you may experience discomfort though I wouldn’t say pain as you’ve described. And yes, eating too quickly can cause again discomfort. You can even have the foamies if something is too heavy, coarse or you eat to quickly but you’ve haven’t experienced that.
I’d still check with your surgeon or go to a hospital because you really shouldn’t be experiencing pain as strong as you’ve indicated.