Hi, I'd like to help you with your question.
It is possible for you to feel stressed or anxious even if you are not consciously aware of it.
Developing a tolerance to feelings of stress or anxiety can come after you have had it for a while. It comes to the point that you no longer notice feeling this way because your body and mind are used to the higher level of intensity. In contrast, if you take a very anxious person and suddenly make them relax, they notice that they feel very tired and very unusual. The same if you take a relaxed person and make them anxious about something. They will react strongly because it is not something they are used to. But if you gradually build up the stress and anxiety, you may not notice it as much.
If your doctor is suggesting that you are stressed or anxious, then there needs to be some evidence of why you are feeling this way. Do you have a high level of stress in your life? Have you recently gone through a difficult time or some type of trauma? You may feel that you worked through something but in fact you are still feeling the effects of the incident.
You could also be depressed. Depression can range from a reaction to something that happened in our lives to a biological cause. Anxiety can accompany depression and can even push the depression into the background so it becomes the main symptom.
The best way to find out if you are experiencing these symptoms and why you may have them is to have an evaluation done by a therapist. The therapist is trained to screen out any diagnosis that is not compatible with your symptoms. They will also screen you for any possible anxiety, depression or even stress disorder. To find a therapist, ask your doctor for a referral. Or search on line at http://therapists.psychologytoday.com/rms/.
I hope this has helped you,