Stomach Pain Before And After Eating. Doctor Advised Nexium Syrup. Blood And Stool Tests Normal. Suggestion?

Hi there 3 or so weeks ago I started to get bad stomach pain in the upper abdomen and everywhere after eating usually half an hour or an hour later every day it seemed to get a little worse until the forth day I decided I need to see a doctor. I saw a doctor and He just told me it is most likely gastritis and gave me Nexuim saying I will feel better in 2 days and sent me on my way. I told the doctor that it is urgent I get fixed because in a week and a bit that I leave for Sea and work on a prawn trawler for 4 months straight without hardly going to ports on land. Six days past and Everyday I was getting worse terrible pain in my upper stomach and ribs so i went to another doctor (only having 3 days till departing for sea) She told me I needed to get the test where i need to blow into something but I had no time for it because I had to stop nexium for a week so it would give me a result. So instead I gave her a stool sample and blood test and she would ring me when the results came back and let me know. By the time I was at sea i started to get bad heartburn and acid reflux more after eating then stomach pain. (I have been eating very healthy the whole time and trying to stay away from acid forming food and eating more alkaline forming food. ) Anyway I got the results and apparently there is nothing wrong with me I just have a sensitive stomach. I have never ever gotten this pain or trouble in my life. I stopped Nexium and I did start to feel a little better. Its been 10 days now and I have been working 15 hour nights and sleep in the day for 4-5 hours and I do this every day its extremly hard back breaking work and I cant always eat the right foods but I stay away from fatty artificial foods. During the night when I work I get bad tummy pains and cramps that come and go when I go to the toilet sometimes however it is not diharria its just normal but I guess constipated. Last night I ate a little red meat with veggies and an hour later threw it all up. I have lost a dress size and now randomly 2 days ago I noticed a little tinny squishy light bump between my anus and vagina more on the anus side and now today it has gotten a little bigger and its painful when i touch it. I washed it with antibacterial wash but I am extremly worried and stressed and confused out in the middle of the ocean and I am please asking you for your help. What is wrong with me?? Should I be staying away from acid forming food? everything even healthy food hurts but fruit is usually okay but I cant survive on just that I need a lot of energy for the line of work I do... I dont drink. I dont smoke. I dont eat bad food. Please help me..
Regards
Ange