You are having anxiety attacks it seems. There is usually an underlying cause. Mine was caused by emotional abuse that made me feel worthless. In these feelings, i over worry and panic about everything.I have fears that are not very realistic or seem worse then they actually are. This anxiety doesn't take long before it dumps you into depression..and you hit bottom before you recognize ur going downhill. constant Stress is also known to cause memory loss, concentration, and insomnia. When i have these anxieties, i feel tightness in my chest, feel like i can't take full breaths. I experience racing heart-rate, dizziness, racing thoughts, inability to sleep. I feel jittery, shaky, sometimes dizzy. Sometimes i feel like i can't swallow, like my throat is swollen. I hope this helps..