That's just the withdrawal talking. There are physical (runny nose, watery eyes, restless legs, bone/joint pain, etc) and mental aspects (depression, "mind fuck") to withdrawal.
For me personally, during withdrawal I sit around and think about how wrong I've lived my life, all the mistakes I've made, exes I've wronged, etc ad nauseum.
Don't do anything drastic for at least a couple weeks. These aren't your real, baseline feelings.