During seven nekiyim days is woman allowed to soak in bath for refuah?

It is permissible to soak in a bath, especially in your situation where there is a need.

If you are bathing during the day, try and do the morning bedika before bathing. Also, just to mention, one should avoid doing any bedika immediately after bathing, rather preferably wait 15 minutes.

שו”ת אג”מ (יו”ד ח”ב סי’ ע ד”ה ובדבר), שולחן שלמה נדה פ”ז סעי’ יג, שו”ת יביע אומר (ח”ה יו”ד סי’ ט”ז אות ה)