If I undergo suffering now, will my next birth be better? This answer points out that Karma is not something which is accumulated. 

Hence considering karma as just cause &amp; effect, if I undergo suffering now, like disease, disability, etc, will my future births be better since the cause has yielded a result and that cause is exhausted and will not influence my future births any more. So more suffering I undergo now, more causes I am exhausting ?
I never really understood this view, but it seems to have been held by the Niganthas. See MN 101 for a detailed argument against this sort of reasoning (too long to quote here).

Basically, though, it is like saying that if I have taken poison, I should take more poison so I feel the poisoning more quickly and thus somehow work out the result of the original poison quicker. Isn't that a ridiculous idea?

If I have performed karma X in the past that has result A in the future, performing other karmas Y and Z that also have result A doesn't do anything (except perhaps coincidentally - e.g. cutting off my arm means I can't experience pain in my hand) to affect karma X.

Another fallacy here is the idea that experiencing suffering leads to future happiness (in a way that pleasure doesn't). Really, to be objective, your question would have to include pleasure, in which case it would be, "If I undergo pleasure and pain in this life, will my next rebirth be better?" to which the answer is of course no. 

An important concept to always keep in mind, according to the Buddha's teaching, is that pleasure and pain don't lead to pleasure or pain, it is good and evil that lead to pleasure and pain.