How can I remove these blotches on the skin?

Frequency Separation is the technique, you are looking for.

With this, you separate the image into 2 layers. One containing more of the color information and one containing more of the texture and details.

In very short steps:

• Duplicate (cmd+J) your Background layer twice. Rename the top layer "high frequency" and the bottom "low frequency." Then group the two layers (select the two layers & cmd+g)
• With the Low Frequency layer selected, Filter>Gaussian Blur filter and choose a pixel radius with which all the fine details will be blurred. I have mine set at 3.7 but there are some photographers who will set it to 5 so this is just up to your preference in terms of how much detail you want. I personally prefer a lower blur.
• Now select the High Frequency layer and go Image > Apply Image and use these settings: For 8-bit images-> Layer: Select “Low Frequency”, Invert: unchecked, Blending to “Subtract”, Scale: 2, Offset: 128. For 16-bit images-> Layer: Select “Low Frequency”, Invert: checked, Blending to “Add”, Scale: 2, Offset: 0.

Now you're ready to use the clone stamp & spot-healing brush on the "low frequency" layer for your skin problems. Or use blur or healing brush to even out color.

Source: https://studiorosalie.com/blog-all/4-easy-steps-to-create-a-high-frequency-separation-layer

Video Tutorial by phlearn - they also have that as a photoshop action which saves you the hassle of creating the layers manually

https://www.youtube.com/watch?v=ldhG9fmgC7o