Bruising on thighs

Posting a picture - TMI warning

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I recently lost about 12 pounds and have been on a low calorie vegetarian/vegan diet. I also have been working out for about a month. I noticed last week a few random bruises like this on my thighs then I woke up this morning with this huge bruise. My legs have also seemed veinier than normal.

Any idea what it could be from?