By "doctor" I hope you mean specialist gastroenterologist. I am not, my background being more neurological and spine...but coincidentally I had the gastric emptying test and under the care of a professor of gastroenterology.I also had surgery for GERD. So I know my way a little bit around the area.
so anyone suspected of having gastroparesis should be tested for the known causes. Example, diabetes, and if present treated. This may also improve (potentially) the gastroparesis.
However, In terms of diagnosis the American Neurogastroenterology and Motility Society and Society of Nuclear Medicine defines gastric retention more than 60% at 2 h and/or more than 10% at 4 h being diagnostic of gastroparesis.(further reference, Abell TL, Camilleri M, Donohoe K, et al. Consensus recommendations for gastric emptying scintigraphy: a joint report of the American Neurogastroenterology and Motility Society and the Society of Nuclear Medicine. Am J Gastroenterol 2008; 103:753–763). Suggest you look at the scan results and discuss with your gastroenterologist.
In terms of treatment with medication metoclopromide (maxolon, Reglan) is a commonly used anti nausea drug.It is also a strong prokinetic, meaning stimulating gastrointestinal motility. It is a great drug,well tolerated and I have injected it into probably thousands of people including family members.It also comes in tablet form, again I have prescribed many times.HOWEVER, imo, it is not intended for long term use due to some pretty impressive side effects which accrue with chronic use. I have seen cases of "tardive dyskinesis" but not often. I saw one case of "oculogyric crisis" when working A&E in early days of practice.
The humble antibiotic erythromycin is also a prokinetic but again not usually a long term prospect. There are many prokinetics that have been tried but usually causing problems with side effects. Newer prokinetics such as Ghrelin are also around but I have no experience with them.
some of the antidepressants have also been used including the tricyclics which in the case of the latter is a paradoxical effect.
The herbal extract STW5 (iberogast) has also been used.
For the more heroic there are surgical options.[Edit- there are also gastric stimulators and injections (botulinum)]
Traditional dietary recommendations include consuming frequent small meals and avoiding roughage and high fat foods.
As alluded to earlier there is generally poor correlation between test result and symptoms. Secondly, predictors of poor response to treatment include certain symptoms and psychological correlates. The symptoms associated with poor response are overall severity of symptoms (not what you would normally expect),bloating....but not gastric emptying rates. When it comes to surgical non responders subgroups include idiopathic and those with pain requiring chronic opiates (narcotics etc). To me this points to a stress or psychological connection and indeed there are fairly high comorbidites with anxiety and depression and psychological therapies are indeed one of the treatment options for gastroparesis. I emphasize this does not mean it is all in your head, even people with cancer benefit from stress management. The mind and body are inexorably linked...unless you believe rumours started by french philosopher Descartes,lol .
other reference- Curr Opin Gastroenterol. 2012;28(6):621-628.
Hope my ramblings have helped or given you 'food for thought'