Have Large Red Hot Spot On Knees Which Is Not Sore. What Could It Be?
I am sorry about these red spots above your knees. Together, we shall figure out what the cause is and propose solutions.
From the history you have provided and the description of the lesions(lawn mowing, large red spot above both knees, no pains, no itches or swelling) I think you suffered some mild bleeding into the tissues at these points. This is understandable and explained by the fact that during such an activity you make some complex movements several times to get the work well done. This is especially more common when you are not a professional and only get to do this once in a while.
Because you have no other symptoms, the well localised and symmetric nature of these lesions makes the above explanation most likely for now. Unless new symptoms develop, there is no need to panic.
Simply, observe and it should gradually fade away over the days. If exceptionally it doesn't, or gets even bigger and become painful, then you will need some proper questioning, examination and maybe blood tests if deemed necessary.
Why am I not considering insect bites or allergies? Because you have not mentioned any bites and it will be very rare for the bites/allergies to be symmetric. Also, you would have noticed some itching and swelling.
I hope this answers your questions and relieves your worries.
Feel free to return to me and request for more information if need be.
I wish you good health and above all, peace of mind.
Dr. Ditah, MD.