Rash started a couple days ago and has spread from my lower abdomen up to my neck and down my arms

24F I was told to take 20mg zyrtec but it has not improved since I started taking it. Should I go back to an urgent care to get a steroid shot over topical steroids? I noticed the rash starting Thursday on my lower abdomen and in the next 12 hours it had spread up to my neck and it has continued spreading down my arms since. It has started to move down my legs. It is slightly itchy/prickly but definitely not unbearable. I can only handle wearing super soft clothing. The only other symptom I have had is a headache but that could be unrelated. It starts as small red/brown bumps and then the bumps turn into brighter red clumps. There are pictures I have posted on another subreddit.