I have a small pea sized, greenish blue (sumthin like vein) lump on my chin from few mnths. it cums n goes. pains if pressed slightly?

Excisonal biopsy: From the description it seems to be at least 6 mm. In diameter. That fact together with a changing pigmentation in the skin suggests the need for a biopsy. I would likely move to do a biopsy which incorporate a complete excision of the mass, and to do so in a manner that camouflaged the incisional scar within a relaxed skin tension line along the chin itself for best healing.