(Sorry this is a long post)
In Spring 2018 I thought I'd come down with something like flu. It came very suddenly and prior to that I had felt fit and well.
But I had no respiratory symptoms and no fever. Just extreme tiredness, some nausea, headache and that weird malaise you get the first couple of days with flu.
It didn't really go away.
Week 3, I went to see my GP (I'm in UK) He did blood test, urine test and general physical checks in his office (the last two were normal). Everything was normal when I got the result of my blood test too.
In the 4th week I got an upset gut (loose bm's) but only once a day and occasionally twice.
For a week I couldn't eat certain foods or they upset me.
Then that went away, but the "fluey" feelings came and went for the next 2 years.
At one point I went to the dr. again and another doctor saw me that time. She told me it could be "post viral syndrome" and if it went on beyond 6 months, it might be ME/CFS.
I also had a head CT scan and a neurology consultation because of a recurring mild right-side head pain. He also gave me a basic neuro. test and found no abnormality. My blood work was again -normal.
He suggested it might be a form of migraine.
In 2 years I felt I was making some progress, as I had many more times when I didn't feel so bad. I did sometimes get post exertional malaise but I was managing.
Fast forward to Spring 2020. UK hadn't yet gone into full lockdown. It was early March. I suddenly got the upset gut again. It came on out of the blue.
It went on for 9 days and subsided. I ate low fibre food for those 9 days. Then it went for about 10 days, and came back, and went away again.
Then I caught Covid, April 2nd 2020. My gut was okay when I had the worst of Covid, but the loose bm's came back about 3-4 weeks later after I had made a good recovery from Covid.
I got lower abdominal bloating and distension, some discomfort (not bad pain) a feeling like something always creeping around in my lower gut left side, more gas, swollen lower abdomen, which was worse later in the day and OK first thing in the morning.
and on and off loose bowel movements.
Some days with no rhyme or reason I would be okay, but the symptoms kept coming back.
I couldn't eat certain foods like apples, oatcakes, carrots, beetroot, turnip, oranges, tomatoes, lentils, beans, peas, or they went straight through me. I couldn't eat potato skins of grape skins etc. I had to lower fibre intake. If I did that , I could keep more of an even keel.
In the summer 2020 I had another blood test (normal C reactive protein, normal iron levels, normal vitamin levels (no signs of malabsorption), and everything else normal.)
I also had 3 stool tests:
1) fecal occult blood "FIT" test (normal)
2) Calprotectin (normal)
3) lactoferrin (normal.)
The doctor said that there were no red flags at all, signs of parasites, infection, or inflammation, and thought I had IBS.
I then tried the low FODMAP diet for 8 weeks, slowly introducing small amounts of high FODMAP foods one by one.
I discovered a mixed situation. Some low FODMAPs I still couldn't tolerate. But some high FODMAPs were fine with me and caused no upset, and they hadn't done before either.
It seemed more like fibre in fruit and vegetables that upset me more.. Even low FODMAP fruits and veggies. Anything high-fibre got me. Anything low fibre and my gut was calmer.
The gut symtoms went away sometimes and I was normal for a week, or even three weeks, and could eat mostly anything.
Then they would flare up for a few days, and go back to normal again.
I don't get the original fluey symptoms from 2018 now. They have gone. Everything seems to be the IBS now.
I am getting long periods when my gut seems much better and normal, followed by a bad flare up ( not even stress related) which usually lasts a couple of days, then back to pretty normal bm's, but with some lower gut distension and slight windy discomfort at times.
It seems like it will never go away and I always have to be careful what I eat. I had a really healthy diet before this all started.