Feeding tube issue

Just get it changed. It’s not a question of pushing it back. If it’s dislodged it needs changing. I had mine changed once and it’s no problem for one if the nutrition nurses. 
Im afraid that mucositis ( the painful ulceration) is par for the course as is the thick mucous. Rinsing the mouth out with salt and bicarbonate can help as can being properly hydrated which means taking enough water on board. A nebuliser is useful too. His hospital might supply one but they are cheap enough from Amazon. 
Is he on enough analgesia? 
If getting food in is difficult maybe ask for a pump. I had an NG tube in and fed overnight via pump. You can use them with a knapsack in the day but I preferred night as it left me free of all of that in the day. 
Do just let his team know. 
Best of luck 

PS  some people take Carbocysteine which is a mucolytic available on prescription but I don’t know if it comes in liquid form. I managed by steaming my head over hot water a couple of times a day  

Hi I used carbusistine ti thin the mucus mine was in liquid form and was syringes into my n g tube. I had my tube changed after 3 weeks it was a matter of moments for if you be changed . I also had a humidifier which helped at night plus a nebuliser from hospital which I used up to 6 times a day to looses the mucous. My ng tube was a pump fed one with a rucksack which enabled me to feed on the go it’s not for everyone but worked for me. You can also dilute the ensure type drink either with milk or water. My end of week 3 I was on 30 nd cocodomol and uo to 40 mil if oramorph. Personally  yoghurt I couldn’t get down it was to much for my mouth to cope with. I did rinse with lukewarm water salt and baking powder. 
oral hygiene took 45 mins several times a day once I started. 
i am now 4 years post treatment happily living my life. 
hope  thus helps. 

Thanks Dani, he has his weekly review on Monday so will ask them then.He's just managed another Fortisip so we're 2 up on the deal from yesterday ..Thanks for the advice, it's really helpful....He's on 2.5mg of morphine every 4 hours and liquid paracetamol 4 times a day but the team have said this can still be increased...also using the salt and bicarb mouthwash numerous times in the day...

Hi James. That morphine dose is pretty low. I was was on two or three times that fir a while plus long acting morphine twice a day. You could ask about that especially if he is waking in the night to top the oromorph up. 
Have you got the other stuff they give out? 
I had Caphosol and Gelclair plus Difflam mouthwash. 

I would contact the Nutricia nurse helpline if not go to A&E. Hope it gets sorted soon.