What Causes Bruises On Legs And Above Hips?

i have 3 small bruises, that look like someone grabbed me on my left side, above my hips and one on my leg, but didn't doo anything that would have caused them. i have also been tired and really achey, but just figured it was because I am a new mom of an 8 month old and it was my body reacting. should i be worried?