Trouble spots can refer to a variety of physical or mental issues. In this case, the crossword solution is 'ACNE, ' which is a common skin condition that causes redness, inflammation, and sometimes pus-filled bumps on the face, chest, back, and other areas. ACNE is caused by a combination of factors, including hormones, bacteria, and genetics. It is most common in teenagers and young adults, but can affect people of any age.