Bowel problems - what could be going on here?

[Adultchildofelderlyparents]

I had constipation, building up for several days. It got to the point where my abdomen was swollen and hard to touch, and it became painful to bend down or move much. Never had constipation like that before.
I got some senokot tablets from the chemist and took two overnight. I thought it was supposed to soften/induce a bowel movement, but I woke up in the early hours with explosive diarrhoea. Also had a temperature, felt dizzy and almost passed out. This was the early hours of this morning.
Now it's afternoon and my whole abdomen is swollen and painful again, I've also got a blinding headache and feel sick.
I haven't eaten anything different or unusual. Is this just constipation or should I be worried? I feel so ill with it.

You need to seek medical advice. To be that swollen and in that much pain you need someone to check you haven’t got an obstruction somewhere. If you don’t you may need something more gentle like laxido or fybogel to gently induce movement.

I used senokot once and it was the worst night - raging temperature, nausea, I felt so poorly and it didn’t even move anything! It sounds like constipation and then the senokot has irritated your tummy. If it were me I would give it one more day to see if your tummy settles, if it doesn’t I’d call the GP first thing in the morning to ask to be seen. If you’re in a lot of pain and it just really doesn’t feel “right” perhaps try out of hours or 111 now?
Something I find helpful with constipation is drinking loads (about 3 litres) of water each day for a few days. Make sure you keep your electrolytes up though so I would make sure I have in the day something like fruit juice, a banana, and a small salty snack.
For a poorly tummy follow BART - banana apple rice toast. Keep everything very bland and small portions.
Hope you feel better soon!

Ps I’m not a doctor I just have IBS! Only you can decide when you need medical evaluation - if in doubt, err on the side of caution :)

You need to seek medical review today. The diarrhoea might be overflow that is faeces behind an obstruction trying to get past. With the distension, pain and nausea you certainly need to get advice. You may even be advised to attend ED for an abdominal X-ray if there is concern the bowel could be obstructed.

OP did you see the GP? Are you feeling any better?

Thanks everyone for the advice.
@Northby I haven't managed to see anyone! I called my GP early on Monday to try to get an appointment, but didn't manage to get in, so thought I would see how I go and try again on Tuesday. Felt a bit better on Tuesday so didn't call again. Then felt a lot worse today. My GP surgery is useless, they are only doing telephone appointments and they release a certain number at 8am but if you're not quick enough then no chance. I am going to call the NHS 111 people in the morning. My whole abdomen is so painful. I took your advice though and ate banana and some toast, thanks!