What Causes Abdominal Pain, Fever And Nausea Along With Gastritis?

Question : So about 3 weeks ago I started getting abdominal pain with the severity that it would wake me up at night. It was almost like an intense feeling of hunger, like I hadn't eaten in 3 days. This was also accompanied with a fever, nausea, general weakness etc. After a while, my dad was really sick one day and was vomiting every few minutes and put it down to contracting what I had, my sister then caught this off my dad and threw up throughout the night but was better after that, I have not vomited. My sister is now better but me and my dad both still have symptoms of nausea, abdominal pain that feels like intense hunger etc. Now, there are also symptoms that my dad doesn't have that I do. For instance, my bowel habits have changed. I'm going to the toilet less frequently and when I do go, the stool is quite loose and sometimes is greenish, other times is more pale, sometimes normal colour, sometimes with flecks of white, sometimes red tomato skin colours show up in them. When I do go to the toilet, it does not feel like diarrhoea, even though it is loose. Another thing I have noticed is that my bottom is itchy and it ranges in intensity but usually is at it's worst after a shower/ bath. I took a picture and noticed dried little yellow specks around my anus, almost like dry discharge. More recently I have noticed that when I go to empty my bowels, there is also a clear mucusy looking thing in the bowl, separate from the stool. When I went to my GP, she suggested that I have gastritis and prescribed me Gaviscon which I didn't believe because there are too many unexplained symptoms but, I am still taking the gaviscon to see if it works. Do you have any possible diagnosis? Also, I am type 1 diabetic, if that helps with anything