Following surgery I had really very bad constipation. Didn't go for 4 days! I took an Ayurvedic formula that is very gentle in comparison to the nuclear options you are trying. It's called Triphala and was recommended by an Ayurvedic practitioner who is also a doctor. When I was bad I took one three times a day and it definitely helped. It is also good for gynae issues. Try to buy organic. PM me if you want the supplier.
I also used Aloe Vera juice 2ml for every kilogram of body weight once a day. I used Pukka organic. It must be juice from the inner leaf. On special offer at Baldwins baldwins.co.uk/pukka-herbs-...
Drink plenty of fluids throughout the day and stay hydrated. I know that your endo and the opiates are contributing/causing the trouble but dehydration is a big cause of constipation.
Foods I ate were 2 dried prunes soaked for a while in water and eaten before food. They contain sorbitol which promotes peristalsis. Also kiwis and mint tea. Buckets of mint tea. Mint is great fir the digestion and gas etc.
I also recommend lying down and doing some slow deep breathing a few times a day. Good video here
Try mindfulness meditation too. Calming the mind will help relax your bowel muscles. You might find that being on holiday and relaxing will help a lot.
Castor oil was also recommended by the Auyrvedic practitioner but I didn't need to use it. It is very potent and can upset your tummy. The recommendation was to start off slow with about a teaspoon of organic castor oil and see how you feel. Stop if you feel unwell or continue if ok.
I also tried magnesium but I didn't like it. The form to take is powdered magnesium citrate. It is the most easily absorbed form of magnesium. Start off slow with half a teaspoon. A you increase the dose you might get bowel cramps so regulate the dose back down. I don't like this method though. It didn't suit me.
Accupressure will help too. acupressurepointsguide.com/...
Some essential oils are also said to help but I didn't try any. Try searching online for good ones to use.
Whole flax seeds are often recommended but they are oestrogenic and could cause your endo symptoms to flare so best avoided. Chia seeds would be better but they must be soaked in water to form a gel first otherwise they will make matters worse.
Natural Constipation relief ideas found online...I didn't try all of these!...
olive oil 2 x tablespoons on empty stomach
warm water and lemon juice (I drink this first thing every morning)
molasses- 1 teaspoon in warm water then increase to 2 tea if nothing happens
baking soda 1 teaspoon in 1/4 cup warm water, drink fast
coffee!! or tea but caffeine is oestrogenic so be careful
baked potato skin on
baked sweet potato skin on
sauerkraut - I make my own. Very good for digestion and probiotics.
probiotic coconut yoghurt - I used Coyo yoghurt. Expensive but good probiotics. Avoid actimel or live youghurt, dairy is best avoided with endo and actimel is full of sugar and not much else.
It's a case of trial and error. I would avoid any branded OTC products and steer clear of Senna. Your bowels will eventually be unable to work without 'help' if you take Senna.