I was travelling from Tenby South Wales to Carmarthen on the A477 a craft like a cigar pure white in colour appeared out of nowhere in the sky ahead of me at cloud level. It was big like a plane but it appeared white very bright with no markings. I watched expecting to see wings as it turned but then several more appeared out of nowhere behind it all in a line following each other all exactly the same size and colour. I was startled now as more and more appeared. Out of nowhere I counted 17 then lost track as several other craft appeared from nowhere and flew at the side of the line of craft but these rocked side to side like they were swinging on a piece of string. I tried to get my phone out of my pocket to take a picture but they turned in the direction I was going and vanished one by one like they just disappeared into thin air. They made no sound at all .i had my van window open all the only noise was from the few cars in front of my vehicle. It scared me when I thought about it after arriving in Carmarthen and couldn't stop looking up at the skydive checked news and radio but nothing. No reports ? I haven't told anyone as I'm scared of being laughed at but I've seen these craft and can't believe nobody else has reported it. Hope I'm not going nuts? I've been expecting reports on the news but nothing at all! Now I find myself watching the sky...have done all day. I don't know if anybody in the cars in front of me saw them so I don't have any witness to back me up nor any pics...I'm gutted I didn't get any pics or film of them.