Sympathies OP, I am just recovering after a bout of diverticulitis. I was very fortunate in that I went to our local Urgent Treatment Centre after two days of severe abdo pain and fever and I told them I thought it could be diverticular disease/diverticulitis, as both my mother and sister have it, and the symptoms seemed to fit.
They agreed and sent me home with the right antibiotics and arranged for me to be seen the next day in our local hospital's emergency diagnostic unit. I was given a CT scan which confirmed the diagnosis. So from onset of pain to confirmed diagnosis was just three days.
The antibiotics worked quite quickly and the severe pain and fever went. It was a frightening experience though, as they were initially concerned about a potential bowel perforation. I didn't eat at all for about three days, then slowly started eating small amounts of bland food - scrambled eggs, white rice, chicken. It's been just over two weeks now and I've tried slowly adding more fibre but it seems to set things off again (discomfort and cramping rather than the severe pain). The antibiotics had their own side effects, and I've lost quite a lot of weight from not eating much, and have been really tired.
Every time I get a twinge of pain I'm worried it's going to happen again, so I've been struggling a bit with anxiety (which doesn't help any gut related issue but is hard to control). I'm very fearful of the thought of needing surgery.
As you'll know, it's not something that can be cured, all you can do is follow the advice to try to manage it and reduce the risk of future flare ups. I guess that's just something we have to come to terms with and be vigilant and seek immediate treatment if we experience pain and signs of infection.
I need to lose weight and this has made me determined to tackle it, so that if I do ever need surgery in future I'll be in better shape for it.
On a positive note, my mother has had this condition for years, and has only ever needed antibiotics to manage flare ups, so it's not inevitable that it will ever need surgery.
I really hope you are improving and that the drain is working. Best wishes to you OP.