Can betta fish lay eggs without being exposed to another fish

I know it sounds crazy, but my betta fish is bloated in the chest and there are silver things all around his/her bowl. (I know I'm terrible and dont know if its a male or female!) ...It has always lived alone so there would be no chance of breeding. Do they just randomly lay eggs?

yes the females do lay eggs, even without a male

And when your fish is bloated in the chest then it's most likely constipation

Constipation can strike your betta just like it can you. It is unpleasant but can eventually kill your betta if not treated.

CAUSES:

One of the main reasons a betta becomes constipated is because their main diet is too rich. If you are feeding blood worms or brine shrimp on a daily basis, you can give your betta constipation. Another common cause of constipation is lack of variety in a betta's diet. An easy solution for this is alternating between food types for meals, such as a few pellets in the morning and flakes at night, brine shrimp the next day, etc. A third cause of constipation may be overfeeding at meal times.

PREVENTION:

Some betta owners fast (do not feed) their betta for one day per week to cleanse the betta's system. This is a useful method to prevent constipation, especially if live or frozen foods are fed on a regular basis. Another feeding option thought to prevent constipation is splitting a betta's feeding up into two small meals per day, rather than one larger meal. This reduces the amount of food intake at one time and allows the betta's system to process it easier. Always remember a betta's stomach is about the size of his eyeball, so a little food goes a long way. Variety in a betta's diet is important both to prevent constipation, and insure they are receiving the necessary nutrients to stay healthy.