My dad has been diagnosed with stomach cancer and really needed a 8-12hr op.

But because his had a heart attack before his been told they don't think he'd survive it, so started chemotherapy-  but after a few weeks he started coughing up blood, so contacted hospital and they told him to go up there so they could try helping.... 

After 2 days of basically just laying in the hospital bed with no help,  my dad rang me and asked if I pick him up because his discharging himself....  As he was gathering his stuff to leave he noticed someone had put a leaflet about- Deep bone thrombrosis ?(sorry bout spelling),  Anyway he didn't read it- thinking he'd just knocked it- he sat at home for 4 days with a tingling&cold leg, so went back hospital had a scan & was told his got a bloodclot in a archry & it needed removing..... after 2 days of having it removed, his foot was still freezing cold & he had to have below the knee amputation on his right leg.   

So my 1st bit of needed advice is:    Can chemotherapy really be the reason for blood clot and then amputation   OR  with him having diabetes and left laying in hospital bed for 2 days-  should they not have given him a compression sock to help with the blood flow- preventing blood clot and amputation ?.         Cheers 

& even with all the tablets his having to try take - his still in constant stomach pain,   any advice on what we can get him to try ease the pain ?         Cheers.

& his struggling to eat solids most of the time -and hardly drinking fluids because of a  sore throat.   Suggestions again please.   Thankyou