What Causes Insect Bite Like Welts On Legs, Neck And Elbows?

For the pass day and a half, I ve been bitten by some insect (I m guessing) between 20-30 times around the ankles, knees, elbows, and neck. The bites are red welts, similar to mosquito bites, and range from small to large in size (the biggest being on my knee). I ve tried using a Benadryl anti-itch spray to try and relieve the itching but to no avail. I ve showered, washed clothes and blankets, and vaccuumed the furniture just in case of a sort of bug infestion but after my efforts, I still am getting bit. How can I stop these bug bites and/or relieve the itching?