Question: hi I'm doing a case study and I've got some questions

the case is right below

22nd January 2015:
Mr XXXXXXX (Reg) Baxter, date of birth 12/4/1940, is an ex-miner who has been unemployed since 1992 and now retired. He is married with 4 children (3 females and 1 male). He attends his G.P with some concerns he has over his general health. He reports that he has suffered from diarrhoea and lower back pain for the last week, the back pain of which is getting worse. He tells the GP that he feels tired and lethargic and has done for several months. Physical examination and questioning reveals the following:-
Drinks 20 units of alcohol/week
Smokes 10 – 15 cigarettes a day
Height 1.80 metres (5’ 9”)
Weight 95 kg (15 stones)
BP = 160/109 mm Hg
Pulse 82 bpm
Since his wife died, in 2008, he has lived on ready meals and take-away food, but eats vegetarian food (which he refers to as ‘rabbit food’) at his daughter’s, on the first Sunday in the month.

I suspected that he has kidney failure because he drank too much alcohol and heart failure since he relied on ready meals and he felt tired and has high BMI.
also since he has diarrhoea and lower back pain, i thought he might has IBD or colon cancer
is this right diagnosis?

or is there anymore suspected diseases to be checked?