Tremors And Shakes

I will start with some background of my reason to write this, I apologies if you do not find my story well written, but I am having difficulties finding out how to describe my experiences.

I grew up in Denmark and as a kid I did not have an interest in the paranormal, except the usual, scary stories, movies and the like.

About 10 years ago, a friend of mine bought an old farmhouse at the west coast, he asked me to help him with some maintenance tasks, there was a lot of garbage in the old stable, mainly broken plastic tubs, and tarps. The previous owners had used the place to grow marijuana and this was what had been left by the police.

While working in the stable we often heard voices, like a conversation, but could never make out the words.

What happened one evening has followed me since then, and is the reason I am writing my story.

While I was moving some boxes the whole building started to shake, much as I would imagine a earth quake, but this being Denmark we rarely have earth quake at a magnitude you can feel and at this point I had problems staying on my feet and getting out of the building.

Coming out of the stable none of my friends had felt anything, which is impossible as they were sitting on a bench bolted to the wall of the building, we were looking for plausible explanations but could not find any.

Closest road was almost 200 meters down a drive way, so it could not have been a truck, no neighbor building within shouting distance and obviously no subway system in the countryside.

Since that day I have often felt minor tremors or shakes when sitting or lying down, but there is no movement in stuff like lamps or chandeliers or other evidence of movement actually happening.

Often when this happens I hear sounds, voices or see movements out of the corner of my eyes.

Sometimes when I am walking the ground will feel swampy, as if I am walking on wet dirt, or on plywood on top of mud.

At these times I will often be confused or distracted from what I am doing.

Once when I was feeling the tremors the extractor hood in the kitchen turned on both fan and light, and other times I have had bottles falling over, and a recurring problem with stuck keys on keyboards.

I have gone to the doctor with this several times and have had several tests done at the hospital to check if there is any physical reasons for me to feel these tremors, but the doctors have found nothing.

I was wondering if anyone have any ideas as to what this could be.