Hi Samantha
Good news and bad news. IBS is a condition that you will always have. But that really is the only bit of bad news, honestly. the IBS will flare up and die down slowly, not overnight. It is best just to persevere with FODMAP, and not doing anything silly like spicy foods etc. It will all calm down, and you will get into a routine where essentially you will know what foods or liquids (alcohol!) spark off your IBS.
One of the biggest triggers for an IBS flare up and keeping it there is stress. Hence, your worry about it will not help. I know it seems difficult, but try and relax about it all. See IBS not as a thing that will just go with a few tablets, or overnight like the flu, but view it more as part of you like having a dodgy knee. Something that may always be around.
IBS is uncomfortable, not life threatening, it may seem at the moment to be the centre of your world, but it is just a flare up, and I promise if you stick to FODMAP, relax about it (easier said then done I know), it will slowly calm down. A good tool is to have a daily diary that you write down. Mark down how many times you go to the toilet, how you generally feel (Good/OK/Bad), and any symptoms you may have. By doing this over a week or so, you will see your symptoms getting gradually better.
Trust me, I sort of know about IBS, and have also had it for the last 25 years so an old hand.
The night sweats are not related. It is probably function of your being so worried about it/down. It is what we call 'collateral damage' of IBS, not anything to worry about I suggest.
I hope this helps. Seriously, it may seem depressing now, and all us IBS sufferers feel this in a flare up, but it will get much much better. Don't worry, persevere and start your diary.