Anger

I thought I'm done with anger (and negative emotions generally), but lately they've returned. Around March I grew an interest in Buddhism and decided to embrace this life philosophy in order to live a happier, longer, healtier life. Surprisingly, I managed to control my negative feelings quite good, with very short and weak anger and frustration episodes. Until my mental condition got worse. Since then, I get angry easily and for small things, I even have homicidal desires and get really pissed off on a friend of mine when he doesn't reply to my text message questions or changes the subject during conversation. I'm angry on my mother a lot; I'm not pleased if she shows much interest in my condition, like asking if it'd okay if she entreated me to pay an unplanned visit to the store, but I'm not pleased if she forgets I'm sensitive and starts arguing with me either.
I noticed my speech is much more fast-paced than usual.

What should I do to return to my peaceful lifestyle? Meditation, count to 10 and breath, etc. etc.

While meditation and counting to ten do help, you need to see a psychiatrist. One of the symptoms of mania is faster-paced speech. I also hope you are keeping a journal. I think that could help you get to the root of your anger issues.

I used to have a journal, but tore it apart and set it on fire after reading some entries. I absolutely hate my writing style (lots of repeating, nonesense and embarassing stuff that makes me feel ashamed of myself the next day).
I tried to picture a visit at the psychiatrist, but it all turned into me 'begging' for a gun to kill the bastard (psychiatrist) for asking me stupid questions...I doubt I'd be able to express my feelings towards the psychiatrist in such situations, I have always had problems with expressing what I feel.

You could be in a hypomania period now, happens. When I get out of control I know it's time to visit the doc and get back on meds.

If you don't like writing and reading your stuff, try this app here, you just check off stuff and it creates graphs that chart your moods.

Like your avatar, Joy Division is one my favorite bands.

Good Luck!

Yeah, you might be right! Lately I have only had down as hell periods and some mild ones when I just feel sad, no euphoria like in the past.
I hope I won't do any harm during this period.
Thanks a million for the link, I could definitely use that!
What can I say, I love Joy Division!

I have trouble expressing feelings. That is where my frustration/anger is mostly.

I know, sometimes it can be really frustrating for me too. That's why I arranged an appointment to a psychiatrist to see why exactly I've been having these communication problems since childhood...