Sorry but nearly all of this is outdated advice, please see the ABM protocol I linked to - most of these things either have no evidence of benefit or may make things worse. I've copied some of the relevant text below:
Feed on demand. Overfeeding from the affected breast or ‘‘pumping to empty’’ perpetuates a cycle of hyperlactation and is a major risk factor for worsening tissue edema and inflammation.
In some instances, in which the retroareolar region is so edematous and inflamed that no milk is expressible by infant breastfeeding or hand expression, the mother should not continue to attempt feeding from the affected breast during the acute phase. She can feed from the contralateral breast and return to feeding from the affected breast when edema and inflammation subsides.
Edema may resolve more quickly with ice and lymphatic drainage.
Avoid deep massage of the lactating breast. Deep massage causes increased inflammation, tissue edema, and microvascular injury. The most successful technique approximates manual lymphatic drainage with light sweeping of the skin rather than deep tissue massage (and there's a handy diagram showing lymphatic massage AWAY from the nipple, not towards).
Ice and nonsteroidal anti-inflammatory drugs (NSAIDs) can reduce edema and inflammation and provide symptomatic relief and paracetamol can provide analgesia. For example, ice can be applied every hour or more frequently if desired. Ibuprofen can be dosed 800 mg every 8 hours and paracetamol 1,000 mg every 8 hours.
Although heat will vasodilate and may worsen symptoms, it also may provide comfort for some patients. The use of warm showers and antipyretics did not improve mastitis outcomes in a randomized controlled trial.