These lumps/nodules are what they call a fibro rash.
There are a number of different types of skin-related symptoms that occur in fibromyalgia. Many of them are present alongside one another or become chronic problems. Skin-related fibromyalgia symptoms include the following:

Dry Skin – Many people with fibromyalgia are plagued with dry, cracked skin. Dry flaky skin can appear anywhere on the body, but it particularly affects the hands and fingers. Sometimes this dry skin will begin to peel and cause pain and discomfort.
Itchy Skin – Itchy skin is usually one of the most common skin complaints among those with fibromyalgia. Of course dry skin and rashes can make your skin itch but most often, with fibromyalgia, it occurs without any obvious cause. It is known as a sensory itch and has to do with how our body interprets pain signals.
Rashes – People with fibromyalgia often complain of skin rashes. The typical rash associated with fibromyalgia is red and can be flat or raised and bumpy. In some cases, there is also itchiness. Scratching or sun exposure can make the rash burn.
Mottled Skin – The skin of fibromyalgia sufferers often begins to change color, appearance, or tone. Mottled skin is due to blood vessel changes in the skin that cause a blotchy appearance. These blotches can appear anywhere on the body, particularly on the inside of the forearms and thighs.
Bruising – Many of us with fibromyalgia experience unexplained bruising. I often end up with bruises on my arms, legs and other areas of the body and don’t remember bumping into anything.
Painful Skin (Allodynia) – Allodynia is a fairly rare type of pain in which your skin hurts. Allodynia is believed to be a hypersensitive reaction to temperature and stimuli that wouldn’t normally cause pain. Even a light touch to the skin can be unbearable.
If you struggle with intense itching, red rashes or see a huge bruise that you have no memory of creating, you are not alone. These are not symptoms that you would naturally link to fibromyalgia, but they are connected.

I’ve definitely noticed changes to my skin when I started getting fibromyalgia pain. My skin has been super sensitive to things that never bothered me in the past. This last bout, I developed perioral dermatitis. Switched out my fluoride toothpaste for non-fluoride and went through every product in my house that has sodium lauryl sulfate and sodium laureth sulfate or SLS. I was sort of shocked to see the difference in my skin afterwards. It’s still not perfect but it’s definitely improved.

I have the same. Fibro lumps are very common as are changes to our skin.

I have white patches and brown patches as well. Also small bumps .
Skin issues are common with Fibro.
If she's not sure, though, a biopsy could be the answer. I hope it does not come to that for you. I know many of us do have skin issues such as you described.
Wishing you all the best.

I experience dry patchy areas when I’m in a flare. You really can’t see them but my arms itch like hell.