if someone is interested, the correct form of Michał in Vocative case (Wołacz) is Michale (I guess "h" instead of "ch" was a typo)
so muszę + dokonane is for special things and times but muszę + nie dokonane is for general things and times? right?
no, I wouldn't put it that way. I really can't tell you any rule, but I don't
think the auxiliary verb ("musieć" or other) has an influence on the infinitive verb aspect. Maybe someone with fresh linguistic knowledge (mine is very rusty) can explain it better. Just stick to the comments/examples of z_darius in this thread.
But if you want to read my rambling, here are another examples to illustrate how it depends on the context, not on the grammar.
I had to exercise my back muscles - Musiałem/musiałam ćwiczyć mięśnie grzbietu - imperfective.
Muszę pisać ręcznie, ponieważ przez komputer robię coraz więcej błędów. - I have to write by hand, because computer-typing makes me commit more and more spelling errors. - imperfective.
in the second example "pisać" refers to repetitve actions, hence the imperfective form, the same goes for the first sentence (if something repeats itself, it's logically
still incomplete, imperfective, from the narrative point of view
even though you may refer to a period in the past, so gramatically
it's finished - like in the first example, with the past tense).
I remember, studying languages many years ago, that one method was useful to me to learn (or at least to comprehend) the correct use of tenses in English, German, Italian etc. - you have to project two axles - one is referred to the time - hence the decision on using past, present, future tenses, the other axle is more connected with logic, which is different in every language, placing the narrator in a specific point respectively to the action the verb describes. That's why the context is usually so important.
Musiałem wtedy coś brać
, bo nie pamiętam ani bólu, ani cierpienia. - I must have been doing some drugs then, because I can't remember the pain and the suffering. - You place yourself, as the narrator, in the middle of that period, when you were doing drugs. (also repetitive)
Musiałem wtedy coś wziąć
, bo nie pamiętam ani bólu, ani cierpienia. I must have taken some drugs/pills then, because I can't remember the pain and the suffering. - You place yourself, as the narrator, after one specific event, when you took some drugs/pills.
I'm not sure if my English translations gives correctly the meaning, but I felt that I have to use 2 different expressions (do drugs/take drugs) in English, because here comes another factor in the mix: some actions are naturally perfective or imperfective (like "do drugs"), so the verbs that describe those actions tend to be mostly used in one specific aspect (like in my first example, "Musiałem/musiałam ćwiczyć mięśnie grzbietu" - exercising your muscles is a process, lasting in time, requiring repetitions, so it naturally comes with an imperfective verb, the end result of those exercises can be a well developped muscle, so to describe this effect you'd have to use perfective verb: Rozwinąłem silny biceps - I've developped a strong biceps brachii).