Nodules in palm - tenosynovitis?

I have a nodule on my left palm, under my little finger, just above the crease at the palm.

There is a clear swelling in the area obvious on touching and is sensitive to pressure. Gripping things tightly  or pressing the nodule causes pain. I do not appear to have any limitations in mobility of the finger at the moment although there are the few occasional moments when I have felt some discomfort while typing.

My GP believes it is a swelling of the tendon and sheath which is a precursor to trigger finger. She has referred me to a hand specialist and believes that it is likely I will be offered a steriod injection for the condition.

I have two questions:
a) I was under the impression that tenosynovitis normally manifests in the form of difficulties to straighten or flex the finger. I have no such problems. Could it still be a tenosynovitis problem?
b) If it is early stages of tenosynovitis, would splinting/physical therapy be a viable alternative treatment? I have heard that there are some risks involved in steriod injections.

Just some background, I am a 35 year old female with very active use of hands. I type a great deal as a result of work but also do a fair amount of rowing, motorcycling, tennis and manual work which involves a lot of gripping under pressure.

Thanks in advance for your opinions.