Hi, I had a similar probem on holiday last summer, but found it was actually caused by the stick anti-perspirants I was using! The more I was using to mask the problem, the worse the problem became over time.
I finally realised that the stuff was not coming off when I was washing, and was preventing me sweating properly, clogging the pores, and trapping the smell in the surface of my skin.
The answer I found was to regularly use a good dollop of exfliating scrub under my arm, leave it a minute, then scrub off. This took away the dead skin, the residues of anti-perspirant, cleared the blocked pores, and I was soon back to normal!
I realise that this might not work for you, but it might help (paricularly if you can't access good shower regularly). It may also be worth chatting your doctor on your next vist, as these problems can be hormonal, etc.
Good Luck!