We can experience all kinds of bizarre sensations and feelings when doing meditation, even when you've meditated for a long time. Our minds are simply fighting the quiet; we don't want to relax the mind. And often times meditation brings up the subconscious mind. This can be very unsettling at times. We can see where are deepest fears and insecurities lie.
There is this myth that circulates that meditation is always supposed to pleasant. Many times they are anything but pleasant. But, over time, you should develop a greater sense of peace by understanding ultimate reality a little better.
I have a total monkey mind at times. I get obsessive thoughts that usually have to do with others getting in my way and controlling me. I see the worst in people and think how they want to make me unhappy (not everybody). I wake up in the morning, thinking, "Who's going to try to make my life hard today"? I just want to go into a cave. I get feelings of being extremely overwhelmed by other people. And then I go into a loop, obsessing with everything that's wrong with world and how I cannot fix any of it. Never fight your feelings; just be present with them. Let them simply be. Feel them completely in the body. My subconscious mind is still very delusional about ultimate reality.
I work through these issues through vipassana meditation and Tsa Lung exercises. It takes time. I've made progress over the past few years, but those very negative feelings are still there with me almost everyday at different degrees. And I am fine with this. I simply "am" - good, bad, neutral, whatever.
It is normal for meditators to become agitated with others when becoming a serious meditator. We see less and less the point in idle chat and socialization. We see how others are delusional about ultimate reality and how others pander to our defilements. When in solitude, our defilements are less pronounced.
That said, we need to develop loving-kindness and compassion for all beings, even those we cannot stomach (metta). We don't become real friends, however, with those who don't share our values. Also, once you start to begin to understand the Buddhist concept of emptiness, it helps you better deal with unpleasant feelings about others. It does help me.
Our practice must be regular if we really want to make progress. But one thing (and this is best stated by the Zen Buddhists): don't strive to meet a goal - just be in whatever state you're in. In other words, just be present without thinking so much of a goal.
In closing, people with psychosis or extreme mental illness (schizophrenia, bipolar, on verge of suicide etc.) should not be meditate without being under the care of a teacher. And even then, it may not be advised. This is whole other topic, but I just needed to throw that out there.
I wish you great success in your meditation journey. Stick with it. Make sure you are meditating correctly as taught by one of the great schools of Buddhism (Theravada, Zen, Tibetan, etc.)
May we all fulfill our deepest wish: to be truly happy and free from all suffering:)