my ufo encounter

Okay this took place in xalapa mexico, in the summer of 1999. I was ready to go to bed upstairs while visiting relatives in mexico. I was dozing off and was woken up to a low humming noise. At first I though it was the construction behind the house, there is a huge bus factory in the back, it towers the two story house, but all the sounds I have heard from there have been loud clangs never hums, and this hum vibrated my bed. I looked up and saw a bright green light glowing from the window in front of me. Xalapa has no airport and thus I thought there should not be a airplane that low, and also for all my life living there I have never seen a airplane, maybe one big cargo plane fly over but very rarely. This light also could not have come from the factory since it has no lights on the back of the building just a towering solid brick wall. And on the days there is moon the factory hides it so that cancelled out that theory. I remember being scared and just sitting there. I tried to get up but just laid back down. For the following weeks I remained down there I would occasionally wake up with the bottom fitted sheets on the ground or half way off, and the most disturbing would be bloody noses already dried from the nights. I asked my grandma about seeing anything and she said that night she woke to a light from outside but never bothered to go look at it so I know it wasnt a dream. I was just wondering if anybody had any suggestions on this.