Please note that I am not a doctor or medically trained so you should use any advice that I give with caution and check it for yourself.
It does sound like gastroparesis aka delayed gastric emptying. Do you have any signs of thyroid problems?
Presumably you do not take any anticholinergic medications? Lecithin has an opposite effect supplying phosphatidylCholine and also has beneficial effects on cell membranes.
Some causes of gastroparesis
Smooth muscle disorders
Type 2 diabetes - though gastroparesis is less common than for Type 1 diabetes
Functional gastroparesis (type of Gastroparesis)
Vagus nerve surgery
Gastroesophageal reflux disease
BTW lecithin comes in different forms. It is available in eggs, from soya and from sunflower and can be purchased in capsules, gel caps, granules or liquid forms. I was using soy granules but I am now trying sunflower liquid which I received today. It is thick stuff, very thick and does not pour well. I want to use it as an emulsifier with essential oils, the thickness of it is a concern but it should go quite far. I got Now foods sunflower liquid lecithin 16 floz bottle. There is also Genetically-Modified-Organisms and non Genetically-Modified-Organisms varieties, especially of soy.
I will have to work out how I am going to water this thick stuff down. Heating it a bit might help, hopefully.
It might be worth you having a look at your irises because it can show the reasons for why a person gets certain things. Constipation can be caused by repressing emotions, in some people, most notably but unexplainable, water signs seem to be most affected. Repressing sadness, the feeling and the expression of, causes a nerve ring inside the bowel which causes chronic constipation in affected people. The nerve ring restricts nerve impulses to the bowel wall, slowing movement of food. I have this problem myself and I am cancarian and also have nerve rings in the ascending and descending colons. I am attempting to eliminate the beliefs which cause the problems which I got from my mother.
An excellent iris chart>