What causes a white semicircular band on the fingernails?

Hi doctor,

I have noticed something different on the tip of the nails. At the tip of all nails, a band of half-white color has formed and it is going around the circumference of the nail horizontally. They are not an exact horizontal line, but a circular band around the tip of the nail. I am also attaching a picture of my nails for your better understanding. I am not sure whether they were always there or have developed recently. But, I noticed them recently. Please tell me what is the cause of this. I also have some unusual taste in my mouth or tongue. I do not know whether they are related to the nails. But, I have not had this before.

Please help.

Hello doctor,

Thanks for replying.

I do not think that my nails are loosened from beneath. They are very much intact. My concern is that why I have some white semicircular bands on my fingernails. I have searched on the internet and I could not find this type of nail photo. I am not questioning your diagnosis here. Also, I wanted to tell you that in the past month, I was under stress. Could it be the reason? Also, on my skin when I look with full concentration I find very small shiny particles. They are not visible at first look and are difficult to spot, but when try to look under room light or in the open they it is visible. Sometimes, I get itchy bumps for no reason. Hope to find a good reason.

Please suggest.